Use of CTE results in "find table failed" warning

## Bug Report

The "find table failed" warning appears with CTEs. This has the following issues:

1. It is not clear for a user how to fix this or to make a decision on whether it is safe to ignore or not.
2. This seems to affect the plan cache (it only happens if `tidb_enable_prepared_plan_cache` is set to `ON`). Maybe we could use the plan cache but don't. This could impact performance (but likely very minimal).
3. What happens if the table name of CTE also exists as a real table. Would it then enable the plan cache where it might not be safe to do so?

It might be good to replace "find table failed" with something more informative like "failed to find a table in the system catalog, disabling plan cache for this query."

I think this warning should be suppressed for CTE table names.

Note that this message caps the `sql` field of the log message to 256 characters, which might be too short for some queries to identify them.

### 1. Minimal reproduce step (Required)

Run this program and check the logs from `tidb-server`.

```go
package main

import (
"log/slog"
"os"

_ "github.com/go-sql-driver/mysql"
"github.com/google/uuid"
"github.com/jmoiron/sqlx"
)

const (
queryWithUUID = `WITH _users AS (SELECT 1 WHERE 1 <> :accountUUID) SELECT * FROM _users`
)

func main() {
db, err := sqlx.Connect("mysql", "root@tcp(127.0.0.1:4000)/test")
if err != nil {
slog.Error("Failed to connect", slog.Any("error", err))
os.Exit(1)
}

query, args, err := sqlx.Named(queryWithUUID, map[string]interface{}{
"accountUUID": uuid.MustParse("00000000-1111-2222-3333-444444444444"),
})
if err != nil {
slog.Error("Failed to create query", slog.Any("error", err.Error()))
os.Exit(2)
}

userIDs := []int64{}

if err := db.Select(&userIDs, query, args...); err != nil {
slog.Error("Failed to select", slog.Any("error", err.Error()))
os.Exit(3)
}

slog.Info("results", slog.Any("userIDs", userIDs))
}
```

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

Logs without warnings/errors

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

```
[2023/12/08 14:53:44.926 +01:00] [WARN] [plan_cacheable_checker.go:650] ["find table failed"] [error="[schema:1146]Table 'test._users' doesn't exist"] [sql="WITH _users AS (SELECT 1 WHERE 1 <> ?) SELECT * FROM _users"] [table_schema=test] [table_name=_users]
```

Or with JSON log format:
```json
{
"level": "WARN",
"time": "2023/12/08 14:54:57.425 +01:00",
"caller": "plan_cacheable_checker.go:650",
"message": "find table failed",
"error": "[schema:1146]Table 'test._users' doesn't exist",
"errorVerbose": "[schema:1146]Table 'test._users' doesn't exist\ngithub.com/pingcap/errors.AddStack\n\t/home/dvaneeden/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20221009092201-b66cddb77c32/errors.go:174\ngithub.com/pingcap/errors.(*Error).GenWithStackByArgs\n\t/home/dvaneeden/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20221009092201-b66cddb77c32/normalize.go:164\ngithub.com/pingcap/tidb/pkg/infoschema.(*infoSchema).TableByName\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/infoschema/infoschema.go:208\ngithub.com/pingcap/tidb/pkg/infoschema.(*SessionExtendedInfoSchema).TableByName\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/infoschema/infoschema.go:699\ngithub.com/pingcap/tidb/pkg/planner/core.checkTableCacheable\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/planner/core/plan_cacheable_checker.go:641\ngithub.com/pingcap/tidb/pkg/planner/core.(*cacheableChecker).Enter\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/planner/core/plan_cacheable_checker.go:201\ngithub.com/pingcap/tidb/pkg/parser/ast.(*TableName).Accept\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/parser/ast/dml.go:433\ngithub.com/pingcap/tidb/pkg/parser/ast.(*TableSource).Accept\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/parser/ast/dml.go:604\ngithub.com/pingcap/tidb/pkg/parser/ast.(*Join).Accept\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/parser/ast/dml.go:244\ngithub.com/pingcap/tidb/pkg/parser/ast.(*TableRefsClause).Accept\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/parser/ast/dml.go:805\ngithub.com/pingcap/tidb/pkg/parser/ast.(*SelectStmt).Accept\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/parser/ast/dml.go:1477\ngithub.com/pingcap/tidb/pkg/planner/core.IsASTCacheable\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/planner/core/plan_cacheable_checker.go:75\ngithub.com/pingcap/tidb/pkg/planner/core.GeneratePlanCacheStmtWithAST\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/planner/core/plan_cache_utils.go:141\ngithub.com/pingcap/tidb/pkg/executor.(*PrepareExec).Next\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/executor/prepared.go:120\ngithub.com/pingcap/tidb/pkg/session.(*session).PrepareStmt\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/session/session.go:2510\ngithub.com/pingcap/tidb/pkg/server.(*TiDBContext).Prepare\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/server/driver_tidb.go:340\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).HandleStmtPrepare\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/server/conn_stmt.go:71\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).dispatch\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/server/conn.go:1347\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).Run\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/server/conn.go:1101\ngithub.com/pingcap/tidb/pkg/server.(*Server).onConn\n\t/home/dvaneeden/dev/pingcap/tidb/pkg/server/server.go:701\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1650",
"sql": "WITH _users AS (SELECT 1 WHERE 1 <> ?) SELECT * FROM _users",
"table_schema": "test",
"table_name": "_users"
}
```
### 4. What is your TiDB version? (Required)

```
Release Version: v7.6.0-alpha-406-gd23e1c379a
Edition: Community
Git Commit Hash: d23e1c379a520d02d2510f3786cb7138b55887d1
Git Branch: master
UTC Build Time: 2023-12-08 13:52:08
GoVersion: go1.21.0
Race Enabled: false
Check Table Before Drop: false
Store: unistore
```