Enable pending builds parity by default

This change enabled pending builds parity feature flag by default and
also introduced a next feature flag that makes it possible to use the
data stored in `ci_pending_builds` table.

Changelog: performance

changelogs/unreleased/feature-gb-use-pending-builds-table.yml

----
-title: Enable pending builds queue parity
-merge_request: 62195
-author:
-type: performance