Remove InternalDebugger.track_lr_schedulers_update

[carmocca]

What does this PR do?

Part of #9661

Does your PR introduce any breaking changes? If yes, please list them.

Removes InternalDebugger.track_lr_schedulers_update

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[github-actions]

Build Error! No Linked Issue found. Please link an issue or mention it in the body using #<issue_id>

[awaelchli]

LGTM, I couldn't figure out the tests quick enough ^^

[carmocca]

LGTM, I couldn't figure out the tests quick enough ^^

Sorry! I didn't notice you had a draft

[ananthsub]

I love this cleanup! Should we have an issue for tracking the various places the internal debugger is used? That could help coordinate who's working on what

[carmocca]

Should we have an issue for tracking the various places the internal debugger is used? That could help coordinate who's working on what

Done in #9661