kvserver: fix data race in RefreshPolicy

Previously, replica.RefreshPolicy accessed r.shMu.state.Desc directly without
holding r.raftMu or r.mu. This commit fixes that by using the descriptor
obtained earlier from r.DescAndSpanConfig().

Epic: none
Release note: none

Author: wenyihu6

pkg/kv/kvserver/replica.go

@@ -1366,7 +1366,7 @@ func (r *Replica) RefreshPolicy(latencies map[roachpb.NodeID]time.Duration) {
 		// policy bucket. This then controls how far in the future timestamps will
 		// be closed for the range.
 		maxLatency := time.Duration(-1)
-		for _, peer := range r.shMu.state.Desc.InternalReplicas {
+		for _, peer := range desc.InternalReplicas {
 			peerLatency := closedts.DefaultMaxNetworkRTT
 			if latency, ok := latencies[peer.NodeID]; ok {
 				peerLatency = latency