remove occupancy, as it is not available at this level in the iRail api

[nudded]

Description:

Related issue (if applicable): References #20744

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

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• Documentation added/updated in home-assistant.io

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If the code does not interact with devices:

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[nudded]

This solves #20744 (comment) , as the data is simply not present in the upstream API provider. (iRail)

[thibmaek]

Wow! Thanks! I was going to pick this up this weekend @nudded but I'm glad to see you did that already!

Seems like iRail has removed this in their API, it was def. available before.