Fix memcached configuration in local Docker installs

Related: https://github.com/ansible/awx/issues/3719
Signed-off-by: Shane McDonald <me@shanemcd.com>

installer/roles/image_build/files/settings.py

@@ -99,16 +99,4 @@ CHANNEL_LAYERS = {
                 'CONFIG': {'url': BROKER_URL}}
 }
 
-
-CACHES = {
-    'default': {
-        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
-        'LOCATION': '{}:{}'.format(os.getenv("MEMCACHED_HOST", None),
-                                   os.getenv("MEMCACHED_PORT", "11211"))
-    },
-    'ephemeral': {
-        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
-    },
-}
-
 USE_X_FORWARDED_PORT = True