fix(files): improve delete display name when trashbin is disabled

[st3iny]

• Resolves: none

Summary

1. Have an incoming share from another user.
2. Disable files_trashbin.
3. Observe that the three dot menu of the incoming share shows Delete permanently instead of Leave this share. This confuses some users.

Both display names Leave this share and Disconnect storage should not be influenced by the presence of the trashbin (isTrashbinEnabled()).

Before

Leave share	Disconnect from external storage

After

Leave share	Disconnect external storage

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)

[st3iny]

/backport to stable30

[st3iny]

/backport to stable29

[st3iny]

/backport to stable28

[susnux]

Makes sense for me, but lets wait on @skjnldsv as there was a lot of trouble on this action in the past.