Remove excessive grep invocations from oo-scheduled-jobs

A recent change to oo-scheduled-jobs for BZ 1065045 introduced an invocation of grep for every gear on a node.  This is a performance problem for the minutely cron entry, and this patch provides an alternate solution.  In my tests, the elapsed time for the old code was more than 3 seconds, while the new code ran in 0.13 seconds.