storage: terminate nodes in minority on stats mismatch

Following up on cockroachdb#41893, the consistency checker now instructs the
replicas corresponding to the SHA with the lowest multiplicity to
terminate.

Note that this change is a candidate for backporting into 19.2. An "old"
leaseholder will never populate the newly introduced field, and will
always terminate itself. A new leaseholder will populate the field, but
only new nodes will interpret it. In the worst case, the result will be
a consistency failure that does not lead to a fatal error (but collects
RocksDB checkpoints just the same). Since no significant time is usually
spent in a mixed-patch-releases, this is not a concern that outweighs
the benefit of terminating (heuristically) the "right" nodes.

Release note (general improvement): when the replicas within a range
have found to been corrupted, the outliers will be terminated.
Previously, the leaseholder replica would terminate, regardless of
which replicas disagreed with each other. This is expected to curb
the spreading of corrupted data better than the previous approach.