gs: Respect bandwidth limiting

[fd0]

What is the purpose of this change? What does it change?

In 0dfdc11, accidentally we dropped using the provided http.RoundTripper, this commits adds it back.

Was the change discussed in an issue or in the forum before?

Closes #1989

Checklist

• I have read the Contribution Guidelines
• I have added tests for all changes in this PR
• I have added documentation for the changes (in the manual)
• There's a new file in changelog/unreleased/ that describes the changes for our users (template here)
• I have run gofmt on the code in all commits
• All commit messages are formatted in the same style as the other commits in the repo
• I'm done, this Pull Request is ready for review

[codecov-io]

Codecov Report

Merging #2100 into master will decrease coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2100      +/-   ##
==========================================
- Coverage   50.78%   50.73%   -0.06%     
==========================================
  Files         176      176              
  Lines       14165    14168       +3     
==========================================
- Hits         7194     7188       -6     
- Misses       5920     5935      +15     
+ Partials     1051     1045       -6

Impacted Files	Coverage Δ
internal/backend/gs/gs.go	74% <100%> (+0.39%)	⬆️
internal/checker/checker.go	64.54% <0%> (-3.87%)	⬇️
internal/backend/s3/s3.go	60.15% <0%> (-2.26%)	⬇️
internal/archiver/file_saver.go	88.59% <0%> (+7.01%)	⬆️
internal/archiver/blob_saver.go	100% <0%> (+7.4%)	⬆️

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