testlib.site: Fix issues w/ broken sites if reuse is False

In case a test site already exists but is broken, so far we tried to start it anyway, causing the test to fail. This change fixes that, as we no longer start an existing site if we do not reuse it.

Change-Id: I704dd820d192f1f4ca2e90143ad129dc713247a8

tests/testlib/site.py

@@ -1354,14 +1354,20 @@ def get_site(
         logger.debug("Created site %s", site.id)
         return site
 
-    def get_existing_site(self, name: str, init_livestatus: bool = True) -> Site:
+    def get_existing_site(
+        self,
+        name: str,
+        start: bool = True,
+        init_livestatus: bool = True,
+    ) -> Site:
         site = self._site_obj(name)
 
-        if not site.exists():
+        if not (site.exists() and start):
             return site
 
         if init_livestatus:
             site.gather_livestatus_port(from_config=True)
+
         site.start()
         logger.debug("Reused site %s", site.id)
         return site
@@ -1581,7 +1587,7 @@ def get_test_site(
             if os.environ.get("CLEANUP") is None
             else os.environ.get("CLEANUP") == "1"
         )
-        site = self.get_existing_site(name)
+        site = self.get_existing_site(name, start=reuse_site)
         if site.exists():
             if reuse_site:
                 logger.info('Reusing existing site "%s" (REUSE=1)', site.id)