[Go SDK] Lint fixes

[riteshghorse]

Go lint fixes introduced in #24307

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[riteshghorse]

Run Go PostCommit

[codecov]

Codecov Report

Merging #24455 (b803b42) into master (57e5b69) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #24455      +/-   ##
==========================================
- Coverage   73.36%   73.36%   -0.01%     
==========================================
  Files         718      718              
  Lines       97165    97165              
==========================================
- Hits        71287    71284       -3     
- Misses      24531    24533       +2     
- Partials     1347     1348       +1     

Flag	Coverage Δ
go	51.58% <ø> (-0.02%)	⬇️

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Impacted Files	Coverage Δ
sdks/go/pkg/beam/core/runtime/exec/window.go	55.00% <ø> (ø)
sdks/go/pkg/beam/core/metrics/dumper.go	49.20% <0.00%> (-4.77%)	⬇️

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[riteshghorse]

R: @lostluck

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