Misc backend performance improvements (#23244)

* Add additional indicies on event and review tables.  Every events or timeline endpoint filters on event start time and camera, this should speed things up by avoiding a range scan on the table.

* Rewrite to use a CTE to leverage speedups by using sqllite internal optimization to do a single query instead of a starter query to get distinct labels and a subsequent loop of querys per distinct event labels.

Frigate is currently shipping sqlite 3.46.1, which is above the minimum version 3.25 needed for CTEs.

* Collapse a few sequential queries into a single one.

* Use peewee instead of rw sql for the CTE query.

* Slightly simplify review logic and avoid duplicating the json response for empty review IDs.

* Rerun ruff formatting.

* Remove 2x unnecessary index on reviewsegment, remove reference to prior code implementation in comment in event.py

* Editor fail, re-ruff format.

* Remove the CTE and restore the generator with sub-queries, which is more performance (thanks Nick and Blake for testing against your larger DB!)

* Update peewee index migration description

* Add on_conflict_ignore, replacing the try/catch/pass on IntegrityError

* Add a testcase for validating that on_conflict_ignore bypasses what was formerly an IntegrityError

* Change testcase to clarify that it covers the peewee behavior of on_conflict_ignore

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Co-authored-by: Greg <{ID}+{username}@users.noreply.github.com>

migrations/036_add_perf_indexes.py

@@ -0,0 +1,21 @@
+"""Peewee migrations -- 036_add_perf_indexes.py.
+
+Adds composite/single-column indexes to speed up single-camera queries
+issued by the web UI.
+
+"""
+
+import peewee as pw
+
+SQL = pw.SQL
+
+
+def migrate(migrator, database, fake=False, **kwargs):
+    migrator.sql(
+        'CREATE INDEX IF NOT EXISTS "event_camera_start_time" '
+        'ON "event" ("camera", "start_time" DESC)'
+    )
+
+
+def rollback(migrator, database, fake=False, **kwargs):
+    migrator.sql('DROP INDEX IF EXISTS "event_camera_start_time"')