Merge branch 'sh-fix-generators-not-always-working' into 'master'

Fix "rails g migration" not always using migration templates

Closes #52651

See merge request gitlab-org/gitlab-ce!22592

config/initializers/8_metrics.rb

@@ -98,7 +98,11 @@ end
 # check: https://github.com/rspec/rspec-mocks#settings-mocks-or-stubs-on-any-instance-of-a-class
 #
 # Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/33587
-if Gitlab::Metrics.enabled? && !Rails.env.test?
+#
+# In development mode, we turn off eager loading when we're running
+# `rails generate migration` because eager loading short-circuits the
+# loading of our custom migration templates.
+if Gitlab::Metrics.enabled? && !Rails.env.test? && !(Rails.env.development? && defined?(Rails::Generators))
   require 'pathname'
   require 'influxdb'
   require 'connection_pool'