Unexpected "fail to generate plan info" warning log

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

~~Run simple SQLs for sysbench schema~~
Not running anything

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

### 3. What did you see instead (Required)

```javascript wrap
[adapter.go:1864] ["fail to generate plan info"] [backtrace="github.com/pingcap/tidb/pkg/executor.(*ExecStmt).SummaryStmt.func1.1\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:1865\ngithub.com/pingcap/tidb/pkg/executor.(*ExecStmt).SummaryStmt.func1\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:1869\ngithub.com/pingcap/tidb/pkg/util/stmtsummary.newStmtSummaryByDigestElement\n\t/home/fedora/eke/tidb/pkg/util/stmtsummary/statement_summary.go:652\ngithub.com/pingcap/tidb/pkg/util/stmtsummary.(*stmtSummaryByDigest).add.func1\n\t/home/fedora/eke/tidb/pkg/util/stmtsummary/statement_summary.go:604\ngithub.com/pingcap/tidb/pkg/util/stmtsummary.(*stmtSummaryByDigest).add\n\t/home/fedora/eke/tidb/pkg/util/stmtsummary/statement_summary.go:618\ngithub.com/pingcap/tidb/pkg/util/stmtsummary.(*stmtSummaryByDigestMap).AddStatement\n\t/home/fedora/eke/tidb/pkg/util/stmtsummary/statement_summary.go:358\ngithub.com/pingcap/tidb/pkg/util/stmtsummary/v2.Add\n\t/home/fedora/eke/tidb/pkg/util/stmtsummary/v2/stmtsummary.go:541\ngithub.com/pingcap/tidb/pkg/executor.(*ExecStmt).SummaryStmt\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:1975\ngithub.com/pingcap/tidb/pkg/executor.(*ExecStmt).FinishExecuteStmt\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:1363\ngithub.com/pingcap/tidb/pkg/executor.(*ExecStmt).CloseRecordSet\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:1471\ngithub.com/pingcap/tidb/pkg/executor.(*recordSet).Close\n\t/home/fedora/eke/tidb/pkg/executor/adapter.go:210\ngithub.com/pingcap/tidb/pkg/session.(*execStmtResult).Close\n\t/home/fedora/eke/tidb/pkg/session/session.go:2374\ngithub.com/pingcap/tidb/pkg/parser/terror.Call\n\t/home/fedora/eke/tidb/pkg/parser/terror/terror.go:315\ngithub.com/pingcap/tidb/pkg/server/internal/resultset.(*tidbResultSet).Close\n\t/home/fedora/eke/tidb/pkg/server/internal/resultset/resultset.go:78\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).handleStmt\n\t/home/fedora/eke/tidb/pkg/server/conn.go:2055\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).handleQuery\n\t/home/fedora/eke/tidb/pkg/server/conn.go:1774\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).dispatch\n\t/home/fedora/eke/tidb/pkg/server/conn.go:1348\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).Run\n\t/home/fedora/eke/tidb/pkg/server/conn.go:1114\ngithub.com/pingcap/tidb/pkg/server.(*Server).onConn\n\t/home/fedora/eke/tidb/pkg/server/server.go:739"] [error=null]
```

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

master (76133dc2e61b7ecdc929892f783b8acc455a57f2)