Use step parameter when logging metrics with NeptuneLogger

[Raalsky]

What does this PR do?

Neptune has a requirement of strictly increasing steps for series. Back then we've been facing some issues regarding the Lightning integration and the order of steps and we had to leave the default behavior. Looks like Lightning is quite safe now with this assumption and some adjustments were made as well like: #11616 so we can get back there.

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📚 Documentation preview 📚 : https://pytorch-lightning--19126.org.readthedocs.build/en/19126/

[codecov]

Codecov Report

Merging #19126 (4ff870e) into master (df869c9) will decrease coverage by 34%.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19126      +/-   ##
==========================================
- Coverage      83%      49%     -34%     
==========================================
  Files         443      435       -8     
  Lines       36764    36611     -153     
==========================================
- Hits        30617    17977   -12640     
- Misses       6147    18634   +12487     

[AleksanderWWW]

LGTM

[Raalsky]

@Borda @awaelchli Should I do something with the failing checks? Tests on GPUs look to be empty, docs are failing due to HTTPS/pool/retries errors so probably unrelated as well.