Fix exception message in openstack.common.processutils.execute
Fix exception message in openstack.common.processutils.execute

Exception message in 'execute' function has wrong value
for module and function. Remove it as wrong and redundant.

Change-Id: Ia5bb4180dbf0df92bfb986c2ddf8327d5bc08e7c

JioCloud/oslo.concurrency,varunarya10/oslo.concurrency,openstack/oslo.concurrency