Make ldap/groups API call backwards compatible

It now just returns the results of the first server. A new call will replace
the existing to get results for a specific provider

config/gitlab.yml.example

@@ -330,6 +330,6 @@ test:
         user_filter: ''
         group_base: 'ou=groups,dc=example,dc=com'
         admin_group: ''
-        sync_ssh_keys: sshpublickey
+        sync_ssh_keys: false
 staging:
   <<: *base

lib/api/ldap.rb

@@ -10,7 +10,10 @@ module API
       # Example Request:
       #  GET /ldap/groups
       get 'groups' do
-        @groups = Gitlab::LDAP::Adapter.new.groups("#{params[:search]}*", 20)
+        # NOTE: this should be deprecated in favour of /ldap/PROVIDER_NAME/groups
+        # for now we just select the first LDAP server
+        provider = Gitlab::LDAP::Config.servers.first.provider_name
+        @groups = Gitlab::LDAP::Adapter.new(provider).groups("#{params[:search]}*", 20)
         present @groups, with: Entities::LdapGroup
       end
     end

lib/gitlab/ldap/config.rb

@@ -4,6 +4,14 @@ module Gitlab
     class Config
       attr_accessor :provider, :options
 
+      def self.enabled?
+        Gitlab.config.ldap.enabled
+      end
+
+      def servers
+        Gitlab.config.ldap.servers
+      end
+
       def initialize(provider)
         @provider = provider
         @options = config_for(provider)