Do not remove SSO callback template file

In distro installs, the SSO callback template file is created in
/etc/keystone. The 'Retrieve default configuration files from venv' task
copies it from there to a cache folder. If 'keystone_sp' is not provided
the file is being removed, which causes a subsequent run of the role to
fail.

Change-Id: I05df4c2a5f57c7437c008dd73a31b7eda2c3e281

tasks/keystone_post_install.yml

@@ -103,14 +103,3 @@
     - Manage LB
     - Restart uWSGI
     - Restart web server
-
-- name: Clean up Keystone Federation SP SSO callback template
-  file:
-    path: "/etc/keystone/sso_callback_template.html"
-    state: absent
-  when:
-    - keystone_sp == {}
-  notify:
-    - Manage LB
-    - Restart uWSGI
-    - Restart web server