Changes

fix(jobs,prow-jobs): rename job to pull_integration_realcluster_test_next_gen (#3574)

This pull request updates the naming convention for a specific
integration test job in both the Jenkins job DSL script and the Prow
presubmit configuration to ensure consistency and alignment with naming
standards.

### Updates to job naming:

*
[`jobs/pingcap/tidb/latest/pull_integration_realcluster_test_next_gen.groovy`](diffhunk://#diff-0b2218849b61adf414df00b459719558317f2473f12cf3f9d8bbcdac03a7c2aeL4-R4):
Renamed the `jobName` variable from
`pull_integration_real_cluster_next_gen` to
`pull_integration_realcluster_test_next_gen` to reflect the updated
naming convention.
*
[`prow-jobs/pingcap/tidb/latest-presubmits-next-gen.yaml`](diffhunk://#diff-6d136e7cf0b5751935f337e8b7065f23f4f547f7f85072637dbab6476832439eL32-R32):
Updated the `name` field in the presubmit configuration to match the new
job name, ensuring consistency across systems.
 (commit: 5146a1e)