Add universal ctags to zoekt CI image
What does this MR do and why?
Add ctags installation as recommended by universal-ctags
folks: https://github.com/universal-ctags/ctags-docker/blob/master/Dockerfile
Checklist
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(If applicable) Add patches if required for upgrading Ruby version in https://gitlab.com/gitlab-org/gitlab-build-images/-/tree/master/patches/ruby.