Add clean up steps in preparation for re2 v2.0 gem

As mentioned in https://ruby.social/@mudge/111029298058288514, re2
v2.0 will ship with precompiled native gems. In preparation for that,
perform clean up on unnecessary files:

1. As we do with nokogiri and gprc, remove unnecessary precompiled
libraries for unused Ruby versions.

2. For arm64 platforms where we recompile native gems from source, the
`ports` directory holds the abseil-cpp and libre2 tarballs. The
extracted source, headers, and compiled libraries are also stored
there.  These files are not necessary since the final shared library
statically links with the libraries.

These changes are backwards compatible with re2 v1.0 since v1.0
doesn't ship with these files.

Changelog: changed

Author: stanhu

config/projects/gitlab.rb

@@ -261,6 +261,7 @@
 exclude 'embedded/lib/ruby/gems/*/gems/nokogumbo-*/ext'
 exclude 'embedded/lib/ruby/gems/*/gems/rbtrace-*/ext/src'
 exclude 'embedded/lib/ruby/gems/*/gems/rbtrace-*/ext/dst'
+exclude 'embedded/lib/ruby/gems/*/gems/re2-*/ports'
 exclude 'embedded/lib/ruby/gems/*/gems/*pg_query-*/ext'
 
 # Exclude exe files from Python libraries

config/software/gitlab-rails.rb

@@ -138,7 +138,8 @@
       'google-protobuf' => 'lib/google',
       'grpc' => 'src/ruby/lib/grpc',
       'prometheus-client-mmap' => 'lib',
-      'nokogiri' => 'lib'
+      'nokogiri' => 'lib',
+      're2' => 'lib'
     }
 
     # Delete unused shared libraries included in the gems