feat(go): generalize to also support google-api-go-client

[codyoss]

• Loosen regex on regen PR to work for all Go multi client repos
• Only apply stricter filtering for google-cloud-go repo
• Add test for discovery client docs

[codecov]

Codecov Report

Merging #554 into master will decrease coverage by 0.16%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #554      +/-   ##
==========================================
- Coverage   81.45%   81.28%   -0.17%     
==========================================
  Files          43       43              
  Lines        5086     5104      +18     
  Branches      410      373      -37     
==========================================
+ Hits         4143     4149       +6     
- Misses        942      954      +12     
  Partials        1        1              

Impacted Files	Coverage Δ
src/github.ts	77.02% <100.00%> (-0.10%)	⬇️
src/releasers/go-yoshi.ts	93.68% <100.00%> (-0.51%)	⬇️
src/releasers/index.ts	85.41% <0.00%> (-2.09%)	⬇️
src/releasers/java-yoshi.ts	83.92% <0.00%> (-1.08%)	⬇️
src/releasers/simple.ts	91.75% <0.00%> (-1.04%)	⬇️
src/releasers/ruby.ts	35.34% <0.00%> (-0.87%)	⬇️
src/releasers/java-bom.ts	92.91% <0.00%> (-0.79%)	⬇️
src/release-pr.ts	90.18% <0.00%> (-0.64%)	⬇️
src/releasers/ruby-yoshi.ts	27.93% <0.00%> (-0.56%)	⬇️
... and 6 more

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[bcoe]

@codyoss I'll prioritize this work tomorrow 👍

[bcoe]

@codyoss I'm back on my usual schedule next week, and will help you get this over the finish line.