fix(local-controller): include CFG_OPEN in config mask for visible circles

[cristianscheid]

• Related to: https://github.com/nextcloud-gmbh/circles/pull/13

Summary

• the related PR linked above introduced a regression
  • for context, a circle's config is a bitwise integer, as seen here
  • the idea was to not expose the full config of a circle to non-members on GET ocs/v2.php/apps/circles/circles
  • to achieve that, the returned config was stripped down to only Circle::CFG_VISIBLE for non-members
  • however, one oversight is that Circle::CFG_OPEN is also needed by the frontend to decide whether a user can request to join
• this PR fixes that, so when a non-member fetches a "visible to everyone" circle, instead of returning only Circle::CFG_VISIBLE, value of Circle::CFG_OPEN is also returned
• before this fix, if john creates test_team with CFG_VISIBLE and CFG_OPEN enabled, bob can see the circle but cannot request to join
• after this fix, bob can see and use the "request to join" option again, since Circle::CFG_OPEN is included
• all other configs returned on circle object remain hidden for non-members, preserving the intent of the original PR

Screenshots

john's circle	bob screen (before fix)	bob screen (after fix)

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

[cristianscheid]

/backport to stable34

[cristianscheid]

/backport to stable33

[cristianscheid]

/backport to stable32

[cristianscheid]

/backport to stable31