qa: exercise cephsqlite_inject_stat_error_probability under OSD thrashing

Wire the new fault injector into thrashosds-health.yaml at a low
probability so teuthology suites with osd thrasher also add to
ignorelist the expected log messages it can produce.

Fixes: https://tracker.ceph.com/issues/79526
Signed-off-by: Nitzan Mordechai <nmordech@ibm.com>