Remove Workday YAML configuration

[gjohansson-ST]

Breaking change

Configuring Workday via YAML was deprecated in Home Assistant Core 2023.5 and support has now been removed.
The YAML configuration was automatically imported to a config entry by release Home Assistant Core 2023.5. Please remove Workday YAML configuration from your configuration.yaml file.

Proposed change

Remove platform yaml workday, deprecation started in 2023.5 and is now ended after 2 releases.

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

Code owner commands

Code owners of workday can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign workday Removes the current integration label and assignees on the pull request, add the integration domain after the command.

[jbouwh]

Looks good, only question I have is if we should keep the schema for a while and add cv.removed validators for the removed keys. And a a note when to cleanup the platform schema remainders.