data and index are inconsistent when creating unique index with tidb_ddl_enable_fast_reorg

[wjhuang2016]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Here is the test case

func TestCreateUniqueIndexKeyExist(t *testing.T) {
	store, dom := testkit.CreateMockStoreAndDomain(t)

	tk := testkit.NewTestKit(t, store)
	tk.MustExec("use test")
	tk.MustExec("create table t(a int default 0, b int default 0)")
	tk.MustExec("insert into t values (1, 1), (2, 2), (3, 3), (4, 4)")

	tk1 := testkit.NewTestKit(t, store)
	tk1.MustExec("use test")

	stateDeleteOnlySQLs := []string{"insert into t values (5, 5)"}

	d := dom.DDL()
	originalCallback := d.GetHook()
	defer d.SetHook(originalCallback)
	callback := &ddl.TestDDLCallback{}
	onJobUpdatedExportedFunc := func(job *model.Job) {
		if t.Failed() {
			return
		}
		var err error
		switch job.SchemaState {
		case model.StateDeleteOnly:
			for _, sql := range stateDeleteOnlySQLs {
				_, err = tk1.Exec(sql)
				assert.NoError(t, err)
			}
		case model.StateWriteOnly:
			_, err = tk1.Exec("insert into t values (5, 7)")
			assert.NoError(t, err)
			_, err = tk1.Exec("delete from t where b = 7")
			assert.NoError(t, err)
		case model.StateWriteReorganization:
		}
	}
	callback.OnJobUpdatedExported.Store(&onJobUpdatedExportedFunc)
	d.SetHook(callback)
	tk.MustExec("alter table t add unique index idx(a)")
	tk.MustExec("admin check table t")
}

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

test pass.

3. What did you see instead (Required)

admin check table t, [], error stack [admin:8223]data inconsistency in table: t, index: idx, handle: 5, index-values:"" != record-values:"handle: 5, values: [KindInt64 5]"

4. What is your TiDB version? (Required)

master

[wjhuang2016]

Ref #40583