Fix/setup for path optimizations

[salmart-dev]

Summary

setupForPath has a few issues slowing things down:

1. it is currently hammering the oc_mounts table because of the call to getMountForPath which is always executed unless the user or the provider have been fully set up
2. keeps being re-executed if called with $forChildren = false for paths whose parents have not been set up with children and the path is not an MP itself (because we mark the MP as setup, not the path)
3. suffers from the issue that if any code calls setupForPath('/Talk/01'), setupForPath('/Talk/02'), ... setupForPath('/Talk/100') then it would cause N+1 setups

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)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)