Reduce scope of diagnostics tests for rtsp_to_webrtc to not depend on global state

[allenporter]

Proposed change

Remove the part of the test that asserts on global counters that would fail if run multiple times. The intent of the test is to verify that diagnostics are working end to end and so its fine to not assert on the lower level counter details of the diagnostics returned by the rtsp_to_webrtc.

Old behavior:

$ pip3 install pytest-repeat
$ py.test --count=2 tests/components/rtsp_to_webrtc 
...
FAILED tests/components/rtsp_to_webrtc/test_diagnostics.py::test_entry_diagnostics[2-2] - AssertionError: assert {'discovery':... 'webrtc': {}} == {'discovery':... 'webrtc': {}}
...

New behavior:

$  py.test --count=2 tests/components/rtsp_to_webrtc 
...
      38 passed

Reverts #115398 which was not needed.

This test was previously observed as flaky:

• Fix Codecov upload with token #115384
• Adjust importlib helper to avoid leaking memory on re-raise #115377

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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[jbouwh]

I have set out #115426 in the hope to reproduce the previous error.
In a previous run:
https://github.com/home-assistant/core/actions/runs/8638995509/job/23692070713?pr=110950

[jbouwh]

Seems this will be more resilent,
Thnx @allenporter 👍

[jbouwh]

Thnx!