osd: handle case when stat returns with error in get_hash_info

osd: handle case when stat returns with error in get_hash_info

Previously in the case of the error we stored in the cache and
returned HashInfo(ec_impl->get_chunk_count()), which e.g. could
propagate to non-primary shards, introducing inconsistency.

The function's `checks` flag is replaced with `create` flag,
which seems to have more clear meaning here.

In be_deep_scrub the get_hash_info is still called with the
second argument false (i.e. with `create=false`, while previously
it was `checks=false`), which is done intentionally.

Fixes: https://tracker.ceph.com/issues/48959
Signed-off-by: Mykola Golub <mgolub@suse.com>