fix(user_ldap): Do not map groups we do not know if they match filter

[come-nc]

• Resolves: #

Summary

When nesting is enabled, filterValidGroups is supposed to check for each groups if it actually exist, because it may not be visible to Nextcloud. So in this codepath we disable automapping of groups.

That may mean in some cases we do not map a valid group, but it should get mapped sooner or later anyway.
I’m still pondering if this is the best solution.

• Maybe only do that if nesting is enabled? Not clear to me yet if this is the only possible problematic case
• Maybe only do that if $name is not null, as when it is null a search will be used to validate existence anyway.
• If this last point is true, maybe we simply always pass null for $name? Or pass null for $name when nesting is enabled?

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)