fix(client): disable bucket cache if region or endpoint are specified

[shcheklein]

Until (or similar fix) lands fsspec/s3fs#929 we need to do this check to make DataChain work with custom endpoints provided via env vars (e.g. in Studio).

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 87.44%. Comparing base (2364ac2) to head (4634a13).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/datachain/client/s3.py	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #809      +/-   ##
==========================================
- Coverage   87.44%   87.44%   -0.01%     
==========================================
  Files         128      128              
  Lines       11369    11371       +2     
  Branches     1535     1536       +1     
==========================================
+ Hits         9942     9943       +1     
  Misses       1048     1048              
- Partials      379      380       +1     

Flag	Coverage Δ
datachain	87.38% <66.66%> (-0.01%)	⬇️

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