ceph_test_rados_api_tier: increase HitSetTrim timeouts

...so that they pass when they get unlucky with thrashing.

This will vastly decrease the probability of failure, but failure will
always be possible when a timeout is in place.

Fixes: #8193
Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #1727 from ceph/wip-8193

ceph_test_rados_api_tier: increase HitSetTrim timeouts