qa/tasks/ceph_manager.py: ignore errors in test_pool_min_size

qa/tasks/ceph_manager.py: ignore errors in test_pool_min_size

to be specific, ignore errors when querying erasure coded pool's
erasure-code-profile. the pool might be removed after
"test_pool_min_size" lists all pools and before queries the pools'
erasure-code-profile. in that case, we should just continue on with the
next pool.

normally, the pools are created by the "radosbench" tasks. and they
don't delete the ec profiles after removing the ec pools using them, but
i don't want to rely on this fact. so, in this change, the `try` block
guards both `ceph osd pool get <pool_name> erasure_code_profile`
and `ceph osd erasure-code-profile get <profile>` calls.

Fixes: http://tracker.ceph.com/issues/40533
Signed-off-by: Kefu Chai <kchai@redhat.com>