MISMATCH

Analysis:
========
Existing test script makes use of sleep. The failure is
caused due to a race condition between MTR sleep time and
Server sleep time. The grep_pattern command gets fired
before the error throttle actually expires. Making use of
sleep makes the test script behaviour to be non
deterministic.

Fix:
===
Replaced the sleep with DBUG simulation make the throttle
window to expire and test the fix.