`TestKeyspaceGroupMergeIntoDefault` failed

[rleungx]

Flaky Test

Which jobs are failing

    testutil.go:63: 
        	Error Trace:	/home/runner/work/pd/pd/pkg/utils/testutil/testutil.go:63
        	            				/home/runner/work/pd/pd/tests/tso_cluster.go:168
        	            				/home/runner/work/pd/pd/tests/integrations/mcs/tso/keyspace_group_manager_test.go:787
        	Error:      	Condition never satisfied
        	Test:       	TestTSOKeyspaceGroupManager/TestKeyspaceGroupMergeIntoDefault

CI link

https://github.com/tikv/pd/actions/runs/5995496714/job/16258601063?pr=6985

Reason for failure (if possible)

Anything else