Enable bulk-inserts by default

What does this MR do?

refs #196844 (closed)

Before removing the import_bulk_inserts feature flag altogether, let's first enable bulk inserts for everyone by default.

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