Scenario tests started to fail on unexpected relation_id

[mmkay]

In traefik's CI we got a bunch of scenario errors:

______ test_middleware_config[https-True-True-subdomain-ingress-per-unit] ______
Traceback (most recent call last):
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/runner.py", line 341, in from_call
    result: Optional[TResult] = func()
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/runner.py", line 241, in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/threadexception.py", line 87, in pytest_runtest_call
    yield from thread_exception_runtest_hook()
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/threadexception.py", line 63, in thread_exception_runtest_hook
    yield
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/unraisableexception.py", line 90, in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/unraisableexception.py", line 65, in unraisable_exception_runtest_hook
    yield
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/logging.py", line 850, in pytest_runtest_call
    yield from self._runtest_for(item, "call")
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/logging.py", line 833, in _runtest_for
    yield
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/capture.py", line 878, in pytest_runtest_call
    return (yield)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/skipping.py", line 257, in pytest_runtest_call
    return (yield)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/runner.py", line 183, in pytest_runtest_call
    raise e
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/runner.py", line 173, in pytest_runtest_call
    item.runtest()
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/python.py", line 1632, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/.tox/scenario/lib/python3.8/site-packages/_pytest/python.py", line 162, in pytest_pyfunc_call
    result = testfunction(**testargs)
  File "/opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/unittest/mock.py", line 1325, in patched
    return func(*newargs, **newkeywargs)
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/tests/scenario/test_middlewares.py", line 90, in test_middleware_config
    relation = _create_relation(
  File "/home/runner/work/traefik-k8s-operator/traefik-k8s-operator/tests/scenario/test_middlewares.py", line 50, in _create_relation
    return Relation(
TypeError: __init__() got an unexpected keyword argument 'relation_id'

[PietroPasotti]

Fixed in #131