qa/standalone/scrub: increase status updates frequency

qa/standalone/scrub: increase status updates frequency

To prevent test timeouts.
Also - remove a failing assertion on a specific 'pg query'
output, as it is not central to the test.

Fixes: https://tracker.ceph.com/issues/61385
(cherry picked from commit 6850bce554330d09f476d4e2aa8ac6d5e3f8bf12)

Conflict resolution:
- removed references to perf counters (not part of the original fix)
- related conf values in TEST_scrub_test - not removed (as directly
  related)

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>