DM-54457: Avoid unnecessary file size check on remote storage

[dhirving]

When using FormatterV2 to write a file, we now keep track of the file size that it wrote to use when recording validation information in the datastore. This lets us avoid a call to remote storage to retrieve the size of the file after writing it. In particular, this extra call was contributing to performance problems during heavy processing workloads with the FrDF WebDAV implementation.

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes
• (if changing dimensions.yaml) make a copy of dimensions.yaml in configs/old_dimensions

[codecov]

Codecov Report

❌ Patch coverage is 91.42857% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.52%. Comparing base (0bdf4f7) to head (9b31333).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
python/lsst/daf/butler/datastores/fileDatastore.py	70.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1348      +/-   ##
==========================================
- Coverage   89.53%   89.52%   -0.01%     
==========================================
  Files         370      370              
  Lines       50250    50267      +17     
  Branches     5876     5879       +3     
==========================================
+ Hits        44989    45003      +14     
- Misses       3873     3874       +1     
- Partials     1388     1390       +2     

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