mmaprototype: add local lease transfer counter and fix bug

Add a local counter to track lease transfers made during processing of a
single store, and use it to fix the bug where the global counter was
incorrectly used to determine if this store transferred leases.

The local counter is incremented alongside the global counter, which is
still needed for loop termination across all stores. The check at the
end of lease rebalancing now correctly uses the local counter to decide
whether to skip replica transfers for this specific store.

Author: tbg

pkg/kv/kvserver/allocator/mmaprototype/cluster_state_rebalance_stores.go

@@ -234,6 +234,7 @@ func (rs *rebalanceState) rebalanceStore(
 			//
 			// NB: any ranges at this store that don't have pending changes must
 			// have this local store as the leaseholder.
+			localLeaseTransferCount := 0
 			topKRanges := ss.adjusted.topKRanges[localStoreID]
 			n := topKRanges.len()
 			for i := 0; i < n; i++ {
@@ -375,6 +376,7 @@ func (rs *rebalanceState) rebalanceStore(
 				rs.cs.addPendingRangeChange(leaseChange)
 				rs.changes = append(rs.changes, leaseChange)
 				rs.leaseTransferCount++
+				localLeaseTransferCount++
 				if rs.changes[len(rs.changes)-1].IsChangeReplicas() || !rs.changes[len(rs.changes)-1].IsTransferLease() {
 					panic(fmt.Sprintf("lease transfer is invalid: %v", rs.changes[len(rs.changes)-1]))
 				}
@@ -396,7 +398,7 @@ func (rs *rebalanceState) rebalanceStore(
 					break
 				}
 			}
-			if doneShedding || rs.leaseTransferCount > 0 {
+			if doneShedding || localLeaseTransferCount > 0 {
 				// If managed to transfer a lease, wait for it to be done, before
 				// shedding replicas from this store (which is more costly). Otherwise
 				// we may needlessly start moving replicas. Note that the store
@@ -405,7 +407,7 @@ func (rs *rebalanceState) rebalanceStore(
 				// pending from a load perspective, so we *may* not be able to do more
 				// lease transfers -- so be it.
 				log.KvDistribution.VInfof(ctx, 2, "skipping replica transfers for s%d: done shedding=%v, lease_transfers=%d",
-					store.StoreID, doneShedding, rs.leaseTransferCount)
+					store.StoreID, doneShedding, localLeaseTransferCount)
 				return
 			}
 		}