Fix rainbird entity unique ids

[allenporter]

Proposed change

Fix unique ids for rainbird entities as a follow up from #99704 which fixed the config entry unique ids to fix the error message:

2023-09-30 12:37:42.638 ERROR (MainThread) [homeassistant.components.sensor] Platform rainbird does not generate unique IDs. ID 0-raindelay already exists - ignoring sensor.rain_bird_controller_regenverzogerung_l

This happens because it is using the device serial number for the entity unique id, which may be "0". With this PR, only create an entity unique id when there is a config entry unique id. This changes the logic from checking the serial number for existing config entries that may already have a "0" unique id so they keep working as is.

This adds additional tests to verify that the unique ids are not created and the entity names are consistent with the previous names.

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 rainbird integration limit of one rainbird controller #99240
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
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• Tests have been added to verify that the new code works.

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[home-assistant]

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

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