[50%] [Next-Gen] CI support for PD repository

[wuhuizuo]

Some jobs need to be covered for next-gen:

• build and unit test: feat(tikv/pd): add next-gen build and unit test presubmits for pd master #3570
  • feat(prow-jobs/tikv/pd): enable next gen ut for pd #3816

[wuhuizuo]

Ref tikv/pd#9345

The compile command: NEXT_GEN=1 make pd-server, so the only difference is the NEXT_GEN env var.

[wuhuizuo]

Unit test is not stable for group 7, it's an issue to be diagnosed

[wuhuizuo]

plan to start real cluster test in next week.