[gitlab] Update JOBOWNERS after KMT, E2E changes

[KSerrania]

What does this PR do?

Updates the JOBOWNERS file with the recently added KMT and E2E jobs.

Motivation

Send pipeline failure notifications to the correct teams.

Additional Notes

For E2E tests, the jobs are owned by the team that owns the relevant test folder in the CODEOWNERS file. For KMT tests, I put eBPF Platform as the default owner. Please comment if I missed jobs, or if some jobs should be owned by other teams.

Possible Drawbacks / Trade-offs

n/a

Describe how to test/QA your changes

n/a