Changes

chore(pingcap/tidb): add temporary UT fail fast hacks for next-gen (#3698)

This pull request makes two main changes to the TiDB unit test pipeline
configuration. First, it removes the "Debug info" stage to streamline
the pipeline and reduce unnecessary output. Second, it introduces a
temporary hack to modify test configuration files, disabling the "fail
fast" behavior in unit tests to allow tests to continue running after
failures.

Pipeline simplification:

* Removed the `Debug info` stage, which previously printed environment
information and performed network checks, to streamline the pipeline and
reduce noise.

Test configuration adjustments:

* Added a step to temporarily modify `.bazelrc` and `Makefile` to
disable "fail fast" for unit tests by setting `--flaky_test_attempts=1`
and replacing `--test_keep_going=false` with `-k`, allowing more tests
to run even if some fail.
 (commit: bd8ad66)