Delete some comment or messages of keystone_data.sh(removed)

As files/keystone_data.sh has been removed in the commit
https://review.openstack.org/#/c/79366/, we should remove some
related documations and comments.

Change-Id: I7802d0052fa28d8debb7f361d36a4f108869554c

Author: EinstCrazy

HACKING.rst

@@ -250,8 +250,7 @@ These scripts are executed serially by ``exercise.sh`` in testing situations.
   database access from the exercise itself.
 
 * If specific configuration needs to be present for the exercise to complete,
-  it should be staged in ``stack.sh``, or called from ``stack.sh`` (see
-  ``files/keystone_data.sh`` for an example of this).
+  it should be staged in ``stack.sh``, or called from ``stack.sh``.
 
 * The ``OS_*`` environment variables should be the only ones used for all
   authentication to OpenStack clients as documented in the CLIAuth_ wiki page.

doc/source/configuration.rst

@@ -393,7 +393,7 @@ with ``KEYSTONE_CATALOG_BACKEND``:
         KEYSTONE_CATALOG_BACKEND=template
 
 DevStack's default configuration in ``sql`` mode is set in
-``files/keystone_data.sh``
+``lib/keystone``
 
 
 Guest Images

lib/tempest

@@ -23,7 +23,7 @@
 #
 # Optional Dependencies:
 #
-# - ``ALT_*`` (similar vars exists in keystone_data.sh)
+# - ``ALT_*``
 # - ``LIVE_MIGRATION_AVAILABLE``
 # - ``USE_BLOCK_MIGRATION_FOR_LIVE_MIGRATION``
 # - ``DEFAULT_INSTANCE_TYPE``