Move calculation of gitlab templates version out of *show-ci-variables
Problem/Motivation
The reusable code snippet .show-ci-variables does more than just "show" the variables, it executes a curl on scripts/extract-version.php then runs that script. If this snippet is used in another job, eg custom after_script, with the intention of displaying the Templates version, then it is not only wasting resources to get the script and execute it, but it can cause errors and/or not run correctly, and give confusing infomation in the log.
Proposed resolution
It would be preferable to move the curl and execution of the script into a different code reference, say something like .extract-version, and leave the .show-ci-variables to just do the printing. Then the latter can be called in other places too, without the problem of doing the curl and executing the script.