Changes

chore(pipelines/pingcap/tiflash): tiflash next-gen pipeline support master branch (#3555)

This commit modifies the branch patterns in both
`latest-postsubmits.yaml` and `latest-presubmits-next-gen.yaml` to
include the `master` branch alongside the `feature/next-gen` branches.
This change ensures that the CI pipelines correctly handle builds and
tests for the latest developments in both the master and next-gen
feature branches.
 (commit: ad88d29)