Use the system ruby on CI.

ci_scripts/ci_common.sh

@@ -12,17 +12,12 @@ setup_xcode_cloud_environment () {
     # Prevent installing dependencies in system directories
     echo 'export GEM_HOME=$HOME/.gem' >>~/.zshrc
     echo 'export PATH=$GEM_HOME/bin:$PATH' >>~/.zshrc
-    echo 'export PATH="/usr/local/opt/ruby@2.7/bin:$PATH"' >> ~/.zshrc
     echo 'export PATH="/Users/local/Library/Python/3.9/bin:$PATH"' >> ~/.zshrc
 
     export GEM_HOME=$HOME/.gem
     export PATH=$GEM_HOME/bin:$PATH
-    export PATH="/usr/local/opt/ruby@2.7/bin:$PATH"
     export PATH="/Users/local/Library/Python/3.9/bin:$PATH"
 
-    # Things don't work well on the default ruby version
-    brew install ruby@2.7
-
     gem install bundler
 
     bundle config path vendor/bundle