Increase individual test timeout

test_dependent_behind_dequeue is running right at 30 seconds now
(slowed by the addition of nodepool and ansible/git tasks to all
tests).  Increase the timeout to compensate.

Also increase the settle timeout.  Because of the same additions,
some complex jobs take more than 10 seconds to stabilize now.

Change-Id: I7500b55cbe9e349b826760f31168c14087cf236f
diff --git a/tests/base.py b/tests/base.py
index 1b65416..a988e37 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -1559,7 +1559,7 @@
         self.log.debug("Waiting until settled...")
         start = time.time()
         while True:
-            if time.time() - start > 10:
+            if time.time() - start > 20:
                 self.log.error("Timeout waiting for Zuul to settle")
                 self.log.error("Queue status:")
                 for queue in self.event_queues: