unstable test TestGetInstance

[hawkingrei]

Bug Report

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1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

3. What did you see instead (Required)

    dispatcher_test.go:102: 

        	Error Trace:	disttask/framework/dispatcher/dispatcher_test.go:102

        	Error:      	Not equal: 

        	            	expected: "10.123.124.10:32457"

        	            	actual  : "[ABCD:EF01:2345:6789:ABCD:EF01:2345:6789]:65535"

        	            	

        	            	Diff:

        	            	--- Expected

        	            	+++ Actual

        	            	@@ -1 +1 @@

        	            	-10.123.124.10:32457

        	            	+[ABCD:EF01:2345:6789:ABCD:EF01:2345:6789]:65535

        	Test:       	TestGetInstance

https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftidb%2Fghpr_unit_test/detail/ghpr_unit_test/24891/pipeline

4. What is your TiDB version? (Required)

[hawkingrei]

Fixed by #43880