Fix: Make WandbLogger upload models from all ModelCheckpoint callbacks, not just one

[cgebbe]

What does this PR do?

• Given a trainer with wandb logger and log_model=True
• and two ModelCheckpoint callbacks
• When training
• Then only models from one checkpoint are uploaded to wandb.

Two questions

• how shall I add CHANGELOG entry?
• do you want this e.g. squashed in one commit?

Before submitting

• Was this discussed/agreed via a GitHub issue? (not for typos and docs)
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• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs) - yes
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

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📚 Documentation preview 📚: https://pytorch-lightning--20191.org.readthedocs.build/en/20191/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81%. Comparing base (66508ff) to head (25bd9d7).

❗ There is a different number of reports uploaded between BASE (66508ff) and HEAD (25bd9d7). Click for more details.

HEAD has 71 uploads less than BASE

Flag	BASE (66508ff)	HEAD (25bd9d7)
cpu	35	21
lightning	27	16
pytest	25	2
python3.9	10	6
lightning_fabric	7	0
gpu	4	2
python3.11	10	6
python3.10	10	6
python3.12	5	3

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #20191     +/-   ##
=========================================
- Coverage      89%      81%     -8%     
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  Files         267      264      -3     
  Lines       23064    23010     -54     
=========================================
- Hits        20573    18607   -1966     
- Misses       2491     4403   +1912