Changes

feat(prow-jobs/tikv/pd): enable next gen ut for pd (#3816)

This pull request updates the presubmit job configuration for `tikv/pd`
in `prow-jobs/tikv/pd/latest-presubmits-next-gen.yaml` to improve
resource management and prepare for more stable test execution. The main
changes focus on resource allocation and job stability settings.

Resource allocation updates:
* Changed the resource specification for the test container to
explicitly set both `requests` and `limits` for CPU and memory,
increasing the maximum allowed resources for more demanding test runs.

Job stability and configuration:
* Removed the `optional` and `context` fields from the job
configuration, indicating that the test is no longer considered optional
and will be treated as a required check moving forward.
 (commit: 24df4e9)