Remove unused Gerrit and BoringSSL Bot configuration

[andrewhop]

Description of changes:

AWS-LC does not use Gerrit or the Google build server and doesn't need any of this configuration.

Call-outs:

I quickly skimmed these files and didn't find anything useful that we would want to use/keep.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.73%. Comparing base (4924695) to head (085b822).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2316      +/-   ##
==========================================
- Coverage   78.73%   78.73%   -0.01%     
==========================================
  Files         616      616              
  Lines      107589   107588       -1     
  Branches    15285    15285              
==========================================
- Hits        84712    84706       -6     
- Misses      22223    22228       +5     
  Partials      654      654              

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