Remove unneeded indexes on projects table

What does this MR do?

Related issue: #195881 (closed)

This removes indexes that we don't need anymore after changing the "tie breaker" sorting direction. The indexes have been introduced with !22623 (merged) to optimally support the requests. This is not needed anymore since the tie breaker now also changes its sorting direction.

For more details please refer to !22623 (merged).

I've validated that these indexes are not being used on GitLab.com anymore: #195881 (closed) (comment 278816057)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• [-] Separation of EE specific content