Adjust default name in backup service calls to match documentation

[ludeeus]

Breaking change

The default name given to backups created with the hassio.full_backup and hassio.partial_backup services is no longer "" but the UTC date and time the backup was initiated (%Y-%m-%d %H:%M:%S).

Proposed change

This changes the default name to reflect what is stated in the service descriptions and documentaiton.

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 Backup name default not working #94336
• This PR is related to issue:
• Link to documentation pull request:

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[home-assistant]

Hey there @home-assistant/supervisor, mind taking a look at this pull request as it has been labeled with an integration (hassio) you are listed as a code owner for? Thanks!

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[emontnemery]

LGTM, thanks @ludeeus 👍

[emontnemery]

Should we tag this for 2023.6.2?

[ludeeus]

As it changes defaults, I consider it a breaking change.

[frenck]

Thanks, @ludeeus 👍

../Frenck