TestKeyspaceGroupMergeIntoDefault is unstable

[lhy1024]

Flaky Test

Which jobs are failing

2023-08-28T06:18:07.6894310Z     keyspace_group_manager_test.go:655: 
2023-08-28T06:18:07.6894895Z         	Error Trace:	/home/runner/work/pd/pd/tests/integrations/mcs/tso/keyspace_group_manager_test.go:655
2023-08-28T06:18:07.6895645Z         	            				/opt/hostedtoolcache/go/1.21.0/x64/src/runtime/asm_amd64.s:1650
2023-08-28T06:18:07.6897684Z         	Error:      	[]uint32{0x0, 0x3, 0x4, 0x5, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0x10, 0x11, 0x12, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1e, 0x1f, 0x20, 0x21, 0x23, 0x24, 0x25, 0x28, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x32, 0x33, 0x34, 0x36, 0x37, 0x38, 0x39, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x42, 0x43, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x54, 0x55, 0x57, 0x58, 0x5a, 0x5b, 0x5d, 0x5e, 0x63, 0x64, 0x65, 0x66, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x75, 0x76, 0x77, 0x78} does not contain 0x1
2023-08-28T06:18:07.6898207Z         	Test:       	TestTSOKeyspaceGroupManager/TestKeyspaceGroupMergeIntoDefault

CI link

https://github.com/tikv/pd/actions/runs/5996226186/job/16260426220

Reason for failure (if possible)

Anything else

[lhy1024]

it is the same with #6991