Fix LR scheduler getting called excessively with amp

[akihironitta]

WIP

What does this PR do?

Fixes #5558
Redo #9923

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[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. If you need further help see our docs: https://pytorch-lightning.readthedocs.io/en/latest/generated/CONTRIBUTING.html#pull-request or ask the assistance of a core contributor here or on Slack. Thank you for your contributions.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. If you need further help see our docs: https://pytorch-lightning.readthedocs.io/en/latest/generated/CONTRIBUTING.html#pull-request or ask the assistance of a core contributor here or on Slack. Thank you for your contributions.

[akihironitta]

Will continue this after #11755.

[carmocca]

@akihironitta Should we close this? It's not a big priority to fix it. Also the fix should probably be done in PyTorch

[akihironitta]

Yes, let's. For anyone seeing this PR, please refer to the workaround in #5558 (comment).