Clean up duplicate index_vulnerability_occurrences_on_uuid_1

Problem to Solve

There is a duplicate index index_vulnerability_occurrences_on_uuid_1 in the database. We need to remove this redundant index while retaining the more comprehensive index_vuln_findings_on_uuid_including_vuln_id_1 index to improve database performance and reduce overhead.

Reference: !184577 (comment 2429791980)