Remove special cases for the 'ldap' provider

lib/gitlab/ldap/config.rb

@@ -27,8 +27,6 @@ module Gitlab
       def initialize(provider)
         if self.class.valid_provider?(provider)
           @provider = provider
-        elsif provider == 'ldap'
-          @provider = self.class.providers.first
         else
           self.class.invalid_provider(provider)
         end

lib/gitlab/ldap/user.rb

@@ -13,7 +13,7 @@ module Gitlab
         def find_by_uid_and_provider(uid, provider)
           # LDAP distinguished name is case-insensitive
           identity = ::Identity.
-            where(provider: [provider, :ldap]).
+            where(provider: provider).
             where('lower(extern_uid) = ?', uid.downcase).last
           identity && identity.user
         end