Cleanup keystone library

IDENTITY_API_VERSION is hardcoded to 3 in most locations already, drop
the remaining occurrences, but keep the variable definition since some
plugins still depend on it. Drop ENABLE_IDENTITY_V2 which no longer
has any effect.

Amend variable list for bootstrap_keystone().

Signed-off-by: Dr. Jens Harbott <harbott@osism.tech>
Change-Id: I06f476d2105bc6ec2b511fc5effcfcc3973eaf97
diff --git a/stackrc b/stackrc
index ebe472c..62749a7 100755
--- a/stackrc
+++ b/stackrc
@@ -175,21 +175,9 @@
     export PS4='+ $(short_source):   '
 fi
 
-# Configure Identity API version: 2.0, 3
-IDENTITY_API_VERSION=${IDENTITY_API_VERSION:-3}
-
-# Set the option ENABLE_IDENTITY_V2 to True. It defines whether the DevStack
-# deployment will be deploying the Identity v2 pipelines. If this option is set
-# to ``False``, DevStack will: i) disable Identity v2; ii) configure Tempest to
-# skip Identity v2 specific tests; and iii) configure Horizon to use Identity
-# v3. When this option is set to ``False``, the option IDENTITY_API_VERSION
-# will to be set to ``3`` in order to make DevStack register the Identity
-# endpoint as v3. This flag is experimental and will be used as basis to
-# identify the projects which still have issues to operate with Identity v3.
-ENABLE_IDENTITY_V2=$(trueorfalse False ENABLE_IDENTITY_V2)
-if [ "$ENABLE_IDENTITY_V2" == "False" ]; then
-    IDENTITY_API_VERSION=3
-fi
+# Configure Identity API version
+# TODO(frickler): Drop this when plugins no longer need it
+IDENTITY_API_VERSION=3
 
 # Enable use of Python virtual environments.  Individual project use of
 # venvs are controlled by the PROJECT_VENV array; every project with