There were many calls to read_keyspace_mutation. One in each function
that prepares a mutation for some other schema change.
With this patch they are all moved to a single location.
Tests: unit (dev, debug)
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Message-Id: <20190328024440.26201-1-espindola@scylladb.com>