[build] Re-enable bundler cache to try and speed up builds

(cherry picked from commit 24cebeb)

Author: chadlwilson

.github/workflows/maven.yml

@@ -89,7 +89,7 @@ jobs:
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: jruby-${{ matrix.jruby_version }}
-          bundler-cache: 'false' # Need to install later so we can vary from Gemfile.lock as required for JRuby version compatibility
+          bundler-cache: 'true'
           bundler: ${{ startsWith(matrix.jruby_version, '9.3') && '2.3.27' || 'Gemfile.lock' }}
 
       - name: Remove jruby-launcher # Coming from setup-ruby/ruby-build and causes annoying warnings