Switch statistics config to require either/both 'max_age' and 'sampling_size'

[ThomDietrich]

Breaking change

The configuration of statistics sensors has changed:

• The state_characteristic configuration setting is now mandatory.
• The sampling_size configuration setting is now optional and no longer defaults to the arbitrary value 20. Depending on your use case, you can now define sampling_size, max_age, or both. Existing sensors won't behave differently by the change. However, you might want to check whether your currently defined sensors have a meaningful sampling_size configured, or whether you want to remove this setting completely.

Proposed change

This change needs to go into Home Assistant version 2022.12.0.

So far, the statistics component had an implicit configuration of sampling_size: 20. This did (1) confuse users which didn't set any other often more meaningful and higher value for their use case, and did (2) require a user to decide on and configure a reasonable buffer size limit, which is rather tedious for use cases focused on time-bounds rather than sample-size-bounds. Users would work around this issue by e.g. sampling_size: 9999, which is not an acceptable situation.

This PR removes the default sampling_size. Users can now configure max_age OR sampling_size OR both options in the settings of a statistics sensor. If both limits are given, they will be applied equally.

This PR removes the deprecation warnings for sampling_size and state_characteristic. They served their purpose.

All test cases were adapted to the new configuration needs. No new test cases are necessary, as existing ones already check the correct workings of both sampling bounds.

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 Statistics Sensor has no attributes when measuring binary_sensor entities #50837
• This PR is related to issue: Add deprecation warning for statistics integration default buffer_size #69700 and Add binary characteristics, add deprecation warning for optional state_characteristic parameter #60402
• Link to documentation pull request: Document statistics change to require either/both 'max_age' and 'sampling_size' home-assistant.io#24878

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
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• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

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  Updated and included derived files by running: python3 -m script.hassfest.
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  Updated by running python3 -m script.gen_requirements_all.
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• Untested files have been added to .coveragerc.

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[home-assistant]

Hey there @fabaff, mind taking a look at this pull request as it has been labeled with an integration (statistics) you are listed as a code owner for? Thanks!

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[ThomDietrich]

@emontnemery ready for review. Thanks!

[emontnemery]

Thanks, @ThomDietrich 👍