Tests that test the intersection of two focus areas

[gsnedders]

e.g. in https://github.com/web-platform-tests/interop/issues/305:

container-inner-at-rules.html is labelled with interop-2023-container, but actually tests container queries in combination with @property (which would imply also interop-2023-property).

We should have a general policy for what to do about such tests.

[nt1m]

There's a test also both in interop-2023-events and interop-2023-webcompat at the same time