Help with Feature Flag (allow_unsafe_ruby_regexp)


Setup Context:
We are using GitLab Community Edition with an omnibus configuration running on internal infrastructure. This platform was setup several years ago and we have maintained it by using yum to install gitlab-ce package updates at regular intervals, cloning the instance, and then deploying clones of the source instance to production.

Origin of problem:
With the changes made to the RegEx engine in GitLab 11.9.4 some of our platforms CI/CD pipelines broke because they were using lookahead in their configurations. In GitLab 11.9.7 an update was made to enable administrators to enable a feature that would prevent these no longer supported syntax to function without error (see:

My Problem:
I have been unable to determine how to enable the Feature Flag allow_unsafe_ruby_regexp in my environment. The documentation indicates that within the WebGUI there should be an option to enable specific feature flags (“Operations > Feature Flags”), however this menu option does not appear in any of the interfaces or projects that I have looked at. In addition the GitLab Feature Flag API returns an empty list of features when I query it (see:

Currently I suspect that there is a configuration option missing somewhere in our system that is preventing Feature Flags from being configurable, but this is just a guess. My google foo has thus far failed to turn up any instructions, howto, or documentation that has helped me to get this resolved, so I am hoping that someone here can either tell me what files I need to modify to enable this Feature Flag for the entire platform or point me at a page (other than the GitLab docs, which I have reviewed) that might help me figure it out.