Add tracking for promote premium experiment for control

What does this MR do and why?

Adds tracking for the promote premium billing page for the control experience as per https://gitlab.com/gitlab-org/gitlab/-/issues/346273#control and https://gitlab.com/gitlab-org/gitlab/-/issues/346275#note_974406562

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #346273