perf(db): Optimize jobs table indexes

[ChristophWurst]

• Resolves: [Bug]: Obsolete index jobs.job_class_index #49842

Summary

• Drop redundant index on class
• Extend index on time_sensitive to be more useful

For existing installations we will only drop the redundant index. The replacement will be done by the admin via occ. This avoids long downtime and times without the new index.
For new installations the index will exist out of the box.

TODO

• Do

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[ChristophWurst]

time_sensitive isn't as selective as last_checked, so I flipped the order in 9cac577.

I'm setting this PR to draft until we have the best results from production.