[BUG] Fix scheme bug in GCS anonymous mode

[jaychia]

I think the "deadlocking" in #1432 is actually caused by Python's difflib being really slow on the diff of the bad result.

Also, because our io integration tests on that workflow isn't provided with GCP credentials, it is defaulting to the "anonymous" GCS client which is s3 based. We should fix that once we verify that this fix works.

Closes: #1432

[codecov]

Codecov Report

Merging #1443 (81f5b7c) into main (ecb596a) will decrease coverage by 0.01%.
Report is 1 commits behind head on main.
The diff coverage is n/a.

❗ Current head 81f5b7c differs from pull request most recent head 6943118. Consider uploading reports for the commit 6943118 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1443      +/-   ##
==========================================
- Coverage   74.51%   74.51%   -0.01%     
==========================================
  Files          60       60              
  Lines        6035     6034       -1     
==========================================
- Hits         4497     4496       -1     
  Misses       1538     1538              

see 4 files with indirect coverage changes