Async load cannot delete unnecessary items when there is no histogram metadata for the table

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
1. Find the unit test: `TestNoNeedIndexStatsLoading`
```go
func TestNoNeedIndexStatsLoading(t *testing.T) {
store, dom := realtikvtest.CreateMockStoreAndDomainAndSetup(t)
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test;")
tk.MustExec("drop table if exists t;")
// 1. Create a table and the statsHandle.Update(do.InfoSchema()) will load this table into the stats cache.
tk.MustExec("create table if not exists t(a int, b int, index ia(a));")
// 2. Drop the stats of the stats, it will clean up all system table records for this table.
tk.MustExec("drop stats t;")
// 3. Insert some data and wait for the modify_count and the count is not null in the mysql.stats_meta.
tk.MustExec("insert into t value(1,1), (2,2);")
h := dom.StatsHandle()
require.NoError(t, h.DumpStatsDeltaToKV(true))
require.NoError(t, h.Update(context.Background(), dom.InfoSchema()))
// 4. Try to select some data from this table by ID, it would trigger an async load.
tk.MustExec("set tidb_opt_objective='determinate';")
tk.MustQuery("select * from t where a = 1 and b = 1;").Check(testkit.Rows("1 1"))
table, err := dom.InfoSchema().TableByName(context.Background(), ast.NewCIStr("test"), ast.NewCIStr("t"))
require.NoError(t, err)
checkTableIDInItems(t, table.Meta().ID)
}
```
2. Add a single line to the test:
```diff
func TestNoNeedIndexStatsLoading(t *testing.T) {
store, dom := realtikvtest.CreateMockStoreAndDomainAndSetup(t)
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test;")
tk.MustExec("drop table if exists t;")
// 1. Create a table and the statsHandle.Update(do.InfoSchema()) will load this table into the stats cache.
tk.MustExec("create table if not exists t(a int, b int, index ia(a));")
// 2. Drop the stats of the stats, it will clean up all system table records for this table.
tk.MustExec("drop stats t;")
// 3. Insert some data and wait for the modify_count and the count is not null in the mysql.stats_meta.
tk.MustExec("insert into t value(1,1), (2,2);")
h := dom.StatsHandle()
require.NoError(t, h.DumpStatsDeltaToKV(true))
require.NoError(t, h.Update(context.Background(), dom.InfoSchema()))
// 4. Try to select some data from this table by ID, it would trigger an async load.
tk.MustExec("set tidb_opt_objective='determinate';")
tk.MustQuery("select * from t where a = 1 and b = 1;").Check(testkit.Rows("1 1"))
+ require.NoError(t, h.Update(context.Background(), dom.InfoSchema()))
table, err := dom.InfoSchema().TableByName(context.Background(), ast.NewCIStr("test"), ast.NewCIStr("t"))
require.NoError(t, err)
checkTableIDInItems(t, table.Meta().ID)
}
```
3. Start a TiDB cluster but without any TiDB nodes:
```console
tiup playground nightly --db 0
```
4. Change the test case to use the real TiKV:
```diff
- WithRealTiKV = flag.Bool("with-real-tikv", false, "whether tests run with real TiKV")
+ WithRealTiKV = flag.Bool("with-real-tikv", true, "whether tests run with real TiKV")
```
5. Run the test:
```console
go test -timeout 10m -tags intest -run ^TestNoNeedIndexStatsLoading$ github.com/pingcap/tidb/tests/realtikvtest/statisticstest -count=1
```

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

### 3. What did you see instead (Required)
It kept failing.

```console
--- FAIL: TestNoNeedIndexStatsLoading (60.28s)
testkit.go:123: RefreshSession rand seed: 1737128106368940000
testkit.go:123: RefreshSession rand seed: 1737128106446542000
statistics_test.go:304: Timeout: Table ID was not removed from items within the time limit
FAIL
FAIL github.com/pingcap/tidb/tests/realtikvtest/statisticstest 61.582s
FAIL
```

### 4. What is your TiDB version? (Required)

master