Make Brian Williams a local database reviewer

Why is this change being made?

The concept of local reviewers was recently introduced with gitlab-org/gitlab!93552 (merged). This MR designates me as a local database reviewer, meaning that I'm available for database reviews on sectionsec features, but won't be selected for wider database reviews by roulette. I think this is a happy medium for decreasing the load on database reviewers without adding too much to my workload.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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