Don't allow changing device class in template binary sensor options

[emontnemery]

Proposed change

Don't allow changing device class in template binary sensor options

Rationale:
The device class can be overridden from entity options, updating the device class option will then not do anything

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• This PR fixes or closes issue: fixes #
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[MartinHjelmare]

Do we hook into the entity options directly in the config flow that creates the helper entity? Otherwise it seems like not the best UX to set the device class later after creating the entity.

[emontnemery]

@MartinHjelmare No, but I don't think that matters? With this PR the initial device class can be set from the config flow and changed from device options

[MartinHjelmare]

Ok, I thought it was completely removed from the config flow.

[emontnemery]

Ok, I thought it was completely removed from the config flow.

That's what #99718 did, but there was some discussion in the beta channel and the conclusion was to allow setting the device class in the config flow but only update it via entity settings.