Disable hash join v2 in release-8.5 branch by default

[windtalker]

Bug Report

Please answer these questions before submitting your issue. Thanks!

hash join v2 is enabled by default in release-8.5 branch for test purpose, we should disable it before v8.5.0 is released.

1. Minimal reproduce step (Required)

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)