Add new feature category measurement_and_locking to all free user limit files

Summary

Now that there is a new feature category for Free User Limits gitlab-com/www-gitlab-com!113300 (merged) we should add it to all free user limit files.

The feature category to add is: measurement_and_locking

Engineering Details

we can do something like look for all feature_category: :experimentation_conversion and see if they are free user cap files...and look for any code under free_user_cap module in the app as we organized almost all the code under that module - @dstull