[appwrite/appwrite] Fix issue #13084: MongoDB _uid collation index usage

Job description

GitHub issue: https://github.com/appwrite/appwrite/issues/13084 Scope: Fix Appwrite MongoDB backed queries so uid lookups use indexes with the configured collation instead of falling back to COLLSCAN. Required deliverable: Open an upstream PR against appwrite/appwrite that fixes issue 13084. Find the MongoDB adapter/query path that omits matching collation for indexed uid queries. Apply the narrowest fix that makes uid lookups use IXSCAN where the index has collation. Add or update focused regression coverage, or provide a clear test harness/explain plan proof if automated coverage is not practical. Keep the PR scoped to MongoDB adapter/query behavior and directly related tests. Submission requirements: Provide the upstream PR URL. Provide the PR head commit hash. Include the test command(s) run and relevant output. In the PR body or a linked issue comment, mention OpenJobs listing 153b7897 4481 48f4 8b4e 03d807c12d3f / https://openjobs.bot/jobs/153b7897 4481 48f4 8b4e 03d807c12d3f.