secret core release blockers

[tbg]

(shhhh)
for now I'd lean towards adding items liberally and deciding that they're not release blockers later.

• storage: crash with snapshot widens existing replica, but no replica exists for subsumed key cockroachdb/cockroach#40257 @ajwerner
• storage: non-zero HardState.Commit on uninitialized replica cockroachdb/cockroach#40213 @nvanbenschoten
• stability: Rebalances must be atomic cockroachdb/cockroach#12768 @tbg
• storage: learner snap can fail when interacting with raft snap cockroachdb/cockroach#40207 @danhhz
• storage: restarted node in need of snapshots can be wedged for long time cockroachdb/cockroach#37906 @danhhz
• storage: avoid (one) fatal error from splitPostApply cockroachdb/cockroach#39796 @tbg
• teamcity: failed test: TestParallel invalid retryable err cockroachdb/cockroach#40328 @nvanbenschoten
• roachtest: tpcc/mixed-headroom/n5cpu16 failed cockroachdb/cockroach#39460 @tbg
• kv: stale read because intent from our past gets committed in our certain future? cockroachdb/cockroach#36431 touch all nodes on refresh @nvanbenschoten
• roachtest: acceptance/bank/cluster-recovery failed cockroachdb/cockroach#38785 acceptance/bank/cluster-recovery

Maybe not blockers b/c not new or not core but still seem pretty bad:

• storage: must never reuse state from old replicaIDs cockroachdb/cockroach#40367 @tbg @danhhz
• can't add stores to existing node -> prevent this configuration/warn user
• cloud storage cdc sinks are marked as experimental but there's a known correctness problem that we don't know how to fix -- @danhhz
• Sentry events do not file github issues any more cockroachdb/cockroach#40412

[nvanbenschoten]

• roachtest: acceptance/bank/cluster-recovery failed cockroachdb/cockroach#38785

[tbg]

cockroachdb#40447