codeintel: Do not mark index records as deleting

Created by: efritz

The commit resolvability janitor, which periodically tests to make sure each commit with an upload is still resolvable in gitserver and deletes those that aren't, was over-zealously marking index records as DELETING, which is an upload-only state.

We'll need to also send out a migration or run a command in the Cloud db to move indexes from deleting to deleted where they exist now.

Helps #21938