fix(files_sharing): public share popover jumps on options toggle

[ShGKme]

Summary

• Public share creation popover dialog has dynamically added elements like password and date expiration
• On some screen sizes toggling them results in the popover jump (flip)
• placement="auto" fixes the issue
  • Now it is always on the side and moves freely on size change
  • Unlike many other places, it looks well because the trigger is on the page edge
• I don't think a more general solution is needed:
  • The only other similar place on server is the weather status widget, which is less disturbing
• NcPopover's flip=false or shiftCrossAxis do not help. They prevent jump by allowing overflowing...

Before	After

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)

AI (if applicable)

• The content of this PR was partly or fully generated using AI