fix(user_ldap): sync users even when no display name is set

[eyJhb]

• Resolves: New ldap users can't login: LDAP Login: Could not get user object for DN ... Maybe the LDAP entry has no set display name attribute? #39751

Summary

Removes the check for display name when doing batchApplyUserAttributes, as that is no longer a bug anymore (it was first introduced in owncloud/core#20804 ). This works well in combination with #46114 , which also fixes the enforcement of display name + it fixes logic that was applied for both users and groups, even though it only applied to groups.

I think this PR ,as well as the previous linked one, we will be able to close this issue #39751 , which is largely misconfiguration, however, there is no need for enforcing display name anymore.

Opening this in the hope of getting someone smarter to say if this is a good/bad idea. Spent most of a day debugging this, and the codebase is still very large to navigate for me.

I'm thinking @come-nc will have some insight this area :) Hopefully tagging is not frowned upon.

TODO

• Should be created as a backbort, as fix(mail): Log hint when mail_from_address may be wrong #46040 also has.

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)