region: remove error return logic (tikv#6982)

ref tikv#6920

Signed-off-by: husharp <jinhao.hu@pingcap.com>

server/core/region.go

@@ -694,14 +694,12 @@ func GenerateRegionGuideFunc(enableLog bool) RegionGuideFunc {
 				(region.GetReplicationStatus().GetState() != origin.GetReplicationStatus().GetState() ||
 					region.GetReplicationStatus().GetStateId() != origin.GetReplicationStatus().GetStateId()) {
 				saveCache = true
-				return
 			}
 			// Do not save to kv, because 1) flashback will be eventually set to
 			// false, 2) flashback changes almost all regions in a cluster.
 			// Saving kv may downgrade PD performance when there are many regions.
 			if region.IsFlashbackChanged(origin) {
 				saveCache = true
-				return
 			}
 			if !origin.IsFromHeartbeat() {
 				isNew = true

tests/server/region_syncer/region_syncer_test.go

@@ -234,6 +234,8 @@ func TestPrepareChecker(t *testing.T) {
 	leaderServer = cluster.GetServer(cluster.GetLeader())
 	rc = leaderServer.GetServer().GetRaftCluster()
 	for _, region := range regions {
+		// Need to check if the region was recognized `isNew`.
+		region = region.Clone(core.WithFlashback(true, 1))
 		err = rc.HandleRegionHeartbeat(region)
 		re.NoError(err)
 	}