include/ceph_features: remove ceph_sanitize_features workaround

include/ceph_features: remove ceph_sanitize_features workaround

Way back in 9ea02b84104045c2ffd7e7f4e7af512953855ecd we defined the
SNAPMAPPER feature such that it set bits 32-63 by sign-extending a negative
int32_t to int64_t.  In 4255b5c2fb54ae40c53284b3ab700fdfc7e61748 it was
fixed.  This affected v0.58-657-g9ea02b8 to v0.65-263-g4255b5c.

The workaround santized features whenever the top bit 63 was set to be the
intended set of features (bits 0-32).  Only buggy peers in that range
ever set bit 63.

Since these versions are truly ancient (pre-dumpling) and no clients
should be that old, we are dropping the workaround.  Note that the Linux
kernel client never had this bug: 2b3e0c905af43cfe402a2ef3f800be5dc1684005
went from 30 bits used to 38 bits defiend with the workaround in place.

We deprecate the bit now (i.e., stop paying attention to this bit).  After
another extended period of time we'll eventually be able to retire
and reuse it.

Signed-off-by: Sage Weil <sage@redhat.com>