Quote $@ in ansible-playbook-command.sh

ansible-playbook-command.sh should have quotes around $@ so that the
value can be passed through to ansible-playbook with spaces, etc.

Change-Id: I18b387c84d4e942b3088750bc2871b0200e10071
Closes-Bug: #1748965

releasenotes/notes/quote-$@-a3d47106c9b7eeb6.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - The generated ansible-playbook-command.sh now has quotes around $@ so
+    that the value can be passed through to ansible-playbook with spaces or
+    other characters requiring quotes.

tripleo_common/actions/ansible.py

@@ -462,7 +462,7 @@ class AnsiblePlaybookAction(base.TripleOAction):
                         f.write('%s="%s"\n' % (var, env_variables[var]))
                     f.write('\n')
                     f.write(' '.join(command))
-                    f.write(' $@')
+                    f.write(' "$@"')
                     f.write('\n')
 
                 os.chmod(command_path, 0o750)