Changes

refactor(tekton/v0/triggers/triggers): remove next-gen build triggers (#3813)

- Remove the next-gen build triggers, we have migrated them into
"tekton/v1/triggers/triggers" folder and they will run on Tekton of
`gcp` env.
- Move community, enterprise, and failpoint triggers for git-push-branch
builds to shared location.
- Remove redundant triggers for ticdc, tiflash, cloud-storage-engine,
tikv, and pd.
- Update kustomization.yaml to reflect these changes.
 (commit: b9f22d2)