Changes

fix:  update build and test pipeline for TiFlash (#2719)

- Remove unnecessary line from `pull_unit_test.groovy`
- Update file copying and exclusion in `pull_unit_test.groovy`
- Set git configuration and display git information in
`pull_unit_test.groovy`
- Change ownership and extract files in `pull_unit_test.groovy`
- Modify file and remove unnecessary line in
`pull_build_and_integration_test.groovy`
 (commit: c3aa3ce)