s3: Enforce virtual host style with China endpoint

[vadmeste]

Fixes #2144

[codecov-io]

Codecov Report

Merging #2153 into master will decrease coverage by <.01%.
The diff coverage is 33.33%.

@@            Coverage Diff            @@
##           master   #2153      +/-   ##
=========================================
- Coverage    8.91%    8.9%   -0.01%     
=========================================
  Files          92      92              
  Lines        6845    6847       +2     
=========================================
  Hits          610     610              
- Misses       6103    6105       +2     
  Partials      132     132

Impacted Files	Coverage Δ
cmd/client-s3.go	14.08% <33.33%> (-0.04%)	⬇️

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