Support restoring callbacks' status when predicting

[zihaozou]

Description & Motivation

I implemented EMA using Callback. However, when predicting, the callback's weight isn't loaded back

Pitch

remove the condition at:

pytorch-lightning/src/lightning/pytorch/trainer/connectors/checkpoint_connector.py

Line 400 in f5d8250

if self.trainer.state.fn == TrainerFn.FITTING:

Alternatives

No response

Additional context

No response

cc @Borda

[chualanagit]

@awaelchli would appreciate a review on this PR, thanks!