Removing deplicated option from global.yml file.

The external_ceph_cephx_enabled option is duplicated
in the global.yml. So one of them was deleted.

Change-Id: I2eff2f1d00b3344f90488bfe0477fe800bcaa85f
Closes-Bug: #1702395
Signed-off-by: jangseon ryu <jangseon.ryu@navercorp.com>

etc/kolla/globals.yml

@@ -209,9 +209,6 @@ kolla_internal_vip_address: "10.10.10.254"
 # Set to no if using external Ceph without cephx.
 #external_ceph_cephx_enabled: "yes"
 
-# Set to no if using external Ceph without cephx.
-#external_ceph_cephx_enabled: "yes"
-
 # Ceph is not able to determine the size of a cache pool automatically,
 # so the configuration on the absolute size is required here, otherwise the flush/evict will not work.
 #ceph_target_max_bytes: ""