LDAP: Only the first baseDN is searched when listing LDAP users

[sakjur]

What happened:

When calling pkg/services/ldap Server.Users with a list of users from different BaseDNs only the first BaseDN which contains any of the listed users will be searched and the returned list will be incomplete.

What you expected to happen:

Grafana searches through the different BaseDNs and returns all requested users.

How to reproduce it (as minimally and precisely as possible):

1. Set two SearchBaseDNs.
2. Make sure both have one or more distinct users in them.
3. Search for one user existing in the first baseDN and one from the second baseDN using Server.Users.
4. Only the user existing in the first baseDN is returned.

Anything else we need to know?:

#38891

Environment:

• Grafana version: 6cab44d
• Data source type & version: N/A
• OS Grafana is installed on: N/A
• User OS & Browser: N/A
• Grafana plugins: N/A
• Others: N/A