Closes #19751: Disable occupied Module Bays in form dropdowns

[pheus]

Fixes: #19751

Implements the occupied‑bay UI behavior without adding a private _occupied field to the API.

Update the module_bay form field to use context with disabled_indicator: 'installed_module' so occupied bays are disabled in dropdowns

Notes

• Backward compatible; no database or migration changes
• Keeps the REST surface clean while providing the needed UI parity

[arthanson]

This is showing up in the regular REST API (see screenshot) which with an underscore seems like it is an internal / private parameter?

[pheus]

Thanks for the thoughtful review!

You’re right! The leading underscore makes it look internal. I initially mirrored CabledObjectSerializer (which exposes _occupied), but I agree it’s not ideal here and a brief‑only approach would still require listing it in Meta.fields.

I’ve reworked this to keep the API surface clean:

• Drop _occupied entirely
• Use installed_module as the occupancy signal (included in brief)
• Update the form field context to disable options via installed_module

This preserves the UI behavior without adding a private‑looking field. If you’d prefer an explicit boolean, I can expose a read‑only occupied derived from installed_module. Happy to adjust. Thanks again!

[pheus]

Apologies for the noise! I tried to rename the feature branch in GitHub’s UI to better reflect the updated scope, and that inadvertently auto‑closed this PR. I’ve restored the branch and reopened the PR—no code changes were introduced as part of this. Sorry for the disruption!