gitlab-ctl reconfigure does not remove environment variables previously defined and then removed from gitlab.rb

GitLab version: 11.6.0-ee (4c09765c) Omnibus

Today, we tried to configure our corporate proxy server like it is described in the docs. This caused project pages (GitLab returning a 503 error page) and other functionality depending on communicating with localhost to be unavailable. The no_proxy variable still seems to be ignored, despite it should work as of GitLab 11.6? But that is another issue. Though, the docs should probably give a hint.

The issue

Reverting the configuration changes done to gitlab.rb does not delete the environment variables defined previously.

Workaround

Delete the files at /opt/gitlab/etc/<service>/env/<variable> by hand and restart GitLab with gitlab-ctl restart.