Add Mayra Cabrera as DB Maintainer

Background

• GitLab employee since October 2017 (2 years from now 🎉) - !7822 (merged)
• Involved in different teams throughout my career on GitLab: Former Platform team, Former CI/CD team, Configure and Delivery/Infrastructure (currently).
• Backend Maintainer since May 2019 - !22212 (merged)
• Database Trainee since July 2019 - #4706 (closed)

As Database Trainee,

• I've reviewed from the Database side around 65 merge requests: 80% of those were merged by Database Maintainer without additional comments

• I've improved the Database Review process by

  • Adding and improving the Database Trainee template resemble our other Trainee processes.
    • !25158 (merged)
    • !25518 (merged)
    • !25162 (merged)
  • Documenting and forming the current Database Review Process
    • gitlab-org/gitlab-foss!30156 (closed)
    • gitlab-org/gitlab-foss!30405 (merged)

• I've improved our Database Guidelines by

  • Clarifying the author's responsibility when it comes to a Database Review - gitlab-org/gitlab-foss!32558 (merged)
  • Finishing "Recommended atomic migrations when possible" - gitlab-org/gitlab-foss!31915 (merged)
  • Requiring gitlab-org/gitlab for DB reviews - gitlab-org/gitlab!18072 (merged)
  • Adding a Deleting Migrations guideline - gitlab-org/gitlab!18086 (merged)
  • and many more

• I've also been engaged in DB performance problems and wrote a case study for namespace statistics gitlab-org/gitlab-foss!31547 (merged)

Becoming DB Maintainer

I still feel that I've a lot to learn, but given my DB reviews are mostly accurate, I feel confident that I can help our current DB maintainer with the workload distribution. When coming across an MR that is too complex, and in which I don't feel confident to approve, I'll defer to the other DB Maintainer (@abrandl) or ask for help to either the Database group (@gl-database) or the Database team (#g_database).

I'd also like to state the number of engineers keeps increasing every month. From Maintainer ratios, we're currently 133 backend engineers, so having only 2 DB maintainers is still a significant concern. Because of that:

• I'd like to compromise DB Maintainers to mentor another 3 trainees to become DB maintainer by February 2020 and another 3 by May 2020

This would help us step into the direction of keeping the ratio of engineers per maintainer below 7, which is the same goal for Backend and Frontend departments. I've posted some ideas of how to achieve that on gitlab-org/database-team/team-tasks#10 (comment 234050933)

@abrandl what do you think?