IMPALA-10077: Increase timeout for test_concurrent_invalidate_metadata

test_concurrent_invalidate_metadata runs 20 iterations for concurrent
invalidate metadata commands. Each iteration could take more than 6s.
So it's easy to hit the current timeout limit, 120s. The main purpose of
this test is to detect metadata bugs that could cause invalidate
metadata hanging. It's not for performance. So this patch increases the
timeout limit to 300s to fix the flakiness.

Change-Id: I47e9f4793117b9a726fde165adea68ce31f539a8
Reviewed-on: http://gerrit.cloudera.org:8080/16333
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
diff --git a/tests/custom_cluster/test_concurrent_ddls.py b/tests/custom_cluster/test_concurrent_ddls.py
index 695045b..595ebb7 100644
--- a/tests/custom_cluster/test_concurrent_ddls.py
+++ b/tests/custom_cluster/test_concurrent_ddls.py
@@ -162,7 +162,7 @@
       return True
     return False
 
-  @pytest.mark.timeout(120)
+  @pytest.mark.timeout(300)
   @pytest.mark.execute_serially
   @CustomClusterTestSuite.with_args(
     impalad_args="--use_local_catalog=true",