Revert "Make job registration with labels optional"

This reverts commit aad4917fcee215572401f9b2aa664974f5cbdc19.

We ended up not using this.

Change-Id: I17d37627528ece1880d05e372099e9d1158e1fec
diff --git a/zuul/launcher/ansiblelaunchserver.py b/zuul/launcher/ansiblelaunchserver.py
index 7c7b0cf..6cecb65 100644
--- a/zuul/launcher/ansiblelaunchserver.py
+++ b/zuul/launcher/ansiblelaunchserver.py
@@ -596,11 +596,6 @@
             self.username = config.get('launcher', 'username')
         else:
             self.username = 'zuul'
-        if self.config.has_option('launcher', 'register_labels'):
-            self.register_labels = config.getboolean('launcher',
-                                                     'register_labels')
-        else:
-            self.register_labels = True
         self.callback_dir = callback_dir
         self.library_dir = library_dir
         self.options = options
@@ -740,9 +735,8 @@
             if not matching_labels:
                 return ret
         ret.add('build:%s' % (job['name'],))
-        if self.register_labels:
-            for label in matching_labels:
-                ret.add('build:%s:%s' % (job['name'], label))
+        for label in matching_labels:
+            ret.add('build:%s:%s' % (job['name'], label))
         return ret
 
     def register(self):