[meta] Discussion queries that take more than 15s

@smcgivern Can you please create separate issues for these, schedule them, etc? Per https://gitlab.com/gitlab-com/infrastructure/issues/3291, they should be fixed by February 1st, when these will actually start timing out.

From https://gitlab.com/gitlab-com/infrastructure/issues/3291#note_48499426:

Inserting a system note

Searching all visible issues for a 7 word query, with 2 of the words being 1 or 2 characters: https://gitlab.com/gitlab-org/gitlab-ce/issues/40512

Updating MR

Creating MR

Resolving note

Searching all visible notes for CI_BUILD_NAME

Searching all visible merge requests for aa (somehow counts all visible MRs, without an actual LIKE for %aa%)

Searching all visible snippets for timeout

Listing issues for an issue board

Counting issues on dashboard

Listing issues on dashboard

Listing merge requests on dashboard

Counting merge requests on dashboard

Listing all visible labels in dashboard picker

Listing all visible labels in group