exceptions: Remove exceptions for org.kde.bomber

Current build only shows:

```
{
    "errors": [
        "appstream-id-mismatch-flatpak-id"
    ],
    "warnings": [
        "finish-args-contains-both-x11-and-wayland",
        "appstream-screenshot-missing-caption"
    ],
    "info": [
        "appstream-id-mismatch-flatpak-id: The value of ID tag: org.kde.bomber.desktop in Metainfo does not match the FLATPAK_ID: org.kde.bomber. Please see the docs for more details"
    ],
    "message": "Please consult the documentation at https://docs.flathub.org/docs/for-app-authors/linter"
}
```

This never had any issues KDE/bomber@a5dedf9

flatpak_builder_lint/staticfiles/exceptions.json

@@ -1938,8 +1938,6 @@
         "appstream-id-mismatch-flatpak-id": "appstream-cid predates this linter rule"
     },
     "org.kde.bomber": {
-        "appstream-failed-validation": "grandfathered due to unannounced linter changes",
-        "appstream-missing-developer-name": "grandfathered due to unannounced linter changes",
         "appstream-id-mismatch-flatpak-id": "appstream-cid predates this linter rule"
     },
     "org.kde.bovo": {