Remove unnecessary spaces from messages

If a timeout happens in _status_timeout(), exception message includes
many spaces like the following:

Timed out waiting for thing <<id>>                       to become ..

This patch removes them for log readability.

Change-Id: I5cfea5b447bcdd280b25878e95fa938229038d25
diff --git a/tempest/scenario/manager.py b/tempest/scenario/manager.py
index 9f97964..eeed389 100644
--- a/tempest/scenario/manager.py
+++ b/tempest/scenario/manager.py
@@ -348,8 +348,8 @@
             # so case sensitive comparisons can really mess things
             # up.
             if new_status.lower() == error_status.lower():
-                message = "%s failed to get to expected status. \
-                          In %s state." % (thing, new_status)
+                message = ("%s failed to get to expected status. "
+                           "In %s state.") % (thing, new_status)
                 raise exceptions.BuildErrorException(message)
             elif new_status == expected_status and expected_status is not None:
                 return True  # All good.
@@ -360,8 +360,8 @@
             check_status,
             self.config.compute.build_timeout,
             self.config.compute.build_interval):
-            message = "Timed out waiting for thing %s \
-                      to become %s" % (thing_id, log_status)
+            message = ("Timed out waiting for thing %s "
+                       "to become %s") % (thing_id, log_status)
             raise exceptions.TimeoutException(message)
 
     def _create_loginable_secgroup_rule_nova(self, client=None,