Set Google Tag Manager ID on gitlab.com configuration

What is this issue about

With gitlab-org/gitlab#223768 (closed) we added google tag manager (GTM) script on sign in and trial pages. The GTM.js requires an ID, which we introduced as a configuration in omnibus with gitlab-org/omnibus-gitlab!4473 (merged), called google_tag_manager_nonce_id (within extra)

Request

Set google_tag_manager_nonce_id to GTM-NJXWQL on gitlab.com to enable the script.

Scope Update 2021-04-29

Per discussion with @sytses we have approval to move forward with adding Google Tag Manager to the Sign Up pages (including trial) once we have crafted communications giving advanced notice. This does not ship GTM in the product itself, and does not pass any PII to Google

We do not have approval to do this on the Sign In page until some additional criteria are met around researching the promises we made to our customers and community in the past. This is broken out to a separate issue.