Adding Beta in Enabling Code Suggestions for Gated MVC

Based on slack https://gitlab.slack.com/archives/C048Z2DHWGP/p1675657111623699 ,

change GitLab > Ai Assisted Code Suggestions: Enabled

to

GitLab > AI Assisted Code Suggestions (Beta) : Enabled

cc @nkhalwadekar @tmccaslin @katiemacoy