Recorder improvements

[cdce8p]

Proposed change

Some improvements to the recorder component and its tests in preparation for #45826

Besides some minor typing changes and new test helper functions, the biggest change is that I combined _disconnect_states_about_to_be_purged and _purge_state_ids since I noticed that both should and always will be called together.

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cc: @bdraco

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)
• 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 #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

[bdraco]

Good to review, or should I wait for more changes?

[cdce8p]

@bdraco It's ready for review. Just hope that the tests pass this time. Had one that was a bit flaky (although it worked flawlessly on my machine). If I need to modify something, it will be with a normal commit from now on.

[bdraco]

Tests are passing locally.

[cdce8p]

CI tests are passing now as well

[bdraco]

Lgtm