Make Mark Florian a frontend maintainer of GitLab

Why is this change being made?

Having been a trainee maintainer for around 5 months, and generally performed reviews and written MRs which require few or no further changes after a maintainer review, I think now is the right time to request to become a maintainer!

I've recorded various MRs I've reviewed or written over the last few months in my trainee maintainer issue #5073 (closed). I started noting MRs without using the supplied template, simply writing small notes about them. If necessary, I can expand those to conform to the template.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what