Fix flake8 H404 errors

Fix H404 error and start enforcing it.

Trivialfix

Change-Id: I0c062733660031faf43838798a697daf6674ef14
diff --git a/neutron_tempest_plugin/common/utils.py b/neutron_tempest_plugin/common/utils.py
index c42d984..76fb38f 100644
--- a/neutron_tempest_plugin/common/utils.py
+++ b/neutron_tempest_plugin/common/utils.py
@@ -54,8 +54,8 @@
 
 
 def wait_until_true(predicate, timeout=60, sleep=1, exception=None):
-    """
-    Wait until callable predicate is evaluated as True
+    """Wait until callable predicate is evaluated as True
+
     :param predicate: Callable deciding whether waiting should continue.
     Best practice is to instantiate predicate with functools.partial()
     :param timeout: Timeout in seconds how long should function wait.