Relax the code format for tiflash CI jobs on release-7.5

[JaySon-Huang]

tiflash master branch format codes with clang-format-17. While release-7.5 branch format codes with clang-format-15. It is inconvenient to find a clang-format-15 and format the codes on the old release branch when handling a cherry-pick PR.

Let relax the code format for tiflash CI jobs on release-7.5. So that there is less subtle thing we need to do to provide a urgent hotfix.

Related cherry-pick PR and CI job:

• ddl: Fix default value filling with finer granularity (#10682) pingcap/tiflash#10687
• https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftiflash%2Frelease-7.5%2Fpull_integration_test/detail/pull_integration_test/417/pipeline