search: Remove unindexed search limiting
Created by: tsenart
The existing unindexed search limiting to 200 repo revisions was introduced in #11546 before we had paginated repository resolution, which has a page size of 500 and naturally limits the number of concurrent unindexed searches happening per-request.
This is more than double of the previous limit, but nowhere close the originally reported problematic number of 20k.
Fixes #33214 (closed)
Test plan
Existing tests.