runaway sql feature always query information_schema.tables using internal transaction

[tiancaiamao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

tidb/pkg/resourcegroup/runaway/syncer.go

Line 63 in d64cd8c

sql := fmt.Sprintf(`SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'mysql' AND TABLE_NAME = '%s'`, tableName)

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

Runaway resource control is running background job, querying information_schema.tables every 1s
If there are 1M tables, this single operation cause 100% CPU because scan all 1M information schema tables takes more than 1s

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

[tiancaiamao]

Ref #50959