internal SQL wrongly use get plan cost v1

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

When you enable the flame graph, you will find that some of the internal SQL stacks have stacks that call get_plan_cost_v1, which is clearly incorrect.

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)