Changes

ci(tiflash-scripts): add pull-test, regression, and schrodinger jobs (#4391)

## Summary
- add Prow presubmits for `pingcap-inc/tiflash-scripts`:
  - native `pull-test`
  - jenkins-triggered `pull-regression-test`
  - jenkins-triggered `pull-schrodinger-test`
- add Jenkins pipeline + pod templates for `pull_regression_test` and
`pull_schrodinger_test`
- add CI-side runtime and artifact preparation script for
regression/schrodinger pipelines
- keep Jenkins job DSL minimal for Prow-triggered execution

## Scope
-
`pipelines/pingcap-inc/tiflash-scripts/latest/common/prepare_runtime_and_artifacts.sh`
- `jobs/pingcap-inc/tiflash-scripts/latest/pull_regression_test.groovy`
- `jobs/pingcap-inc/tiflash-scripts/latest/pull_schrodinger_test.groovy`
-
`pipelines/pingcap-inc/tiflash-scripts/latest/pull_regression_test/pipeline.groovy`
-
`pipelines/pingcap-inc/tiflash-scripts/latest/pull_regression_test/pod.yaml`
-
`pipelines/pingcap-inc/tiflash-scripts/latest/pull_schrodinger_test/pipeline.groovy`
-
`pipelines/pingcap-inc/tiflash-scripts/latest/pull_schrodinger_test/pod.yaml`
- `prow-jobs/pingcap-inc/tiflash-scripts/presubmits.yaml`
- `prow-jobs/kustomization.yaml`

## Issue Link
- Parent tracker: #3339
- tiflash-scripts sub-issue: #4307
- regression sub-issue: #4357
- schrodinger sub-issue: #4358
 (commit: 6226f95)