Bump LARGE_OPS number from 50=>100

Now that we have been testing a new LARGE_OPS number in
large-ops-testing for a week with good results, we are satisfied with
the stability of the large-ops test with the increased LARGE_OPS number.

* Stop running large-ops-testing in the silent queue for nova now that
  we have collected enough data.
* Preemptively bump the LARGE_OPS number in large-ops-testing to 175

Change-Id: I9f09ef59a0c6f39da6e8311102c640a6c693d18b
Merge "Bump LARGE_OPS number from 50=>100"