Conditionally add Gitaly deprecation warnings based on ENV variable

config/initializers/deprecations.rb

-if Gitlab.dev_env_or_com?
+if Rails.env.development? || ENV['GITLAB_LEGACY_PATH_LOG_MESSAGE']
   deprecator = ActiveSupport::Deprecation.new('11.0', 'GitLab')
 
   deprecator.behavior = -> (message, callstack) {