Remove `rewrite_sbom_occurrences_query` feature flag

What does this MR do and why?

Remove rewrite_sbom_occurrences_query feature flag, which has been globally enabled for a full week.

This flag enables improved performance for the group-level dependency list. Since enabling the flag, we've seen a huge improvement in query timing. Before, queries for large groups hit the 15 second query timeout frequently. Now, we are seeing query timings of a few seconds in the absolute worst case.

Maximum DB duration:

95th percentile DB duration: