Reducing the running time for test_sync_execute()

This patch reduces the time it takes for the test method
tests.test_utils.SyncExecuteTestCase.test_sync_execute to
complete its work. The runnig time gets reduced from ~5.0 sec
to ~0.3 sec.

Change-Id: I83bbdea4d12aa1ad5aeeccd1a15c4838ef9c419b
Closes-Bug: #1235791