*: fix TestConcurrentlyReset (#6318)

close #6275

Signed-off-by: Ryan Leung <rleungx@gmail.com>

Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>

pkg/tso/global_allocator.go

@@ -543,6 +543,11 @@ func (gta *GlobalTSOAllocator) campaignLeader() {
 	}()
 
 	gta.member.EnableLeader()
+	defer resetLeaderOnce.Do(func() {
+		cancel()
+		gta.member.ResetLeader()
+	})
+
 	// TODO: if enable-local-tso is true, check the cluster dc-location after the primary is elected
 	// go gta.tsoAllocatorManager.ClusterDCLocationChecker()
 	log.Info("tso primary is ready to serve", zap.String("tso-primary-name", gta.member.Name()))