Define Triager Role

[xmulligan]

Introduce a Triager role for Cilium. The Triager should help ensure community contributions and issues are handled in a timely and consistent way.

Responsibilities:

Review community contribution PRs

Apply labels, re-run tests, request rebases, and merge when ready

Review new issues daily, ensure enough detail is provided, and apply appropriate labels (sig/, area/, kind/*)

Flag regressions

Remove needs/triage once categorized

Goal:
Keep community PR and issue queues up to date, while ensuring regressions and important bugs are identified early.

[xmulligan]

I've created cilium/cilium#41871 to write down the process

When that is merged, we should also update https://github.com/cilium/community/blob/main/roles/Triage-Team.md and https://github.com/cilium/community/blob/main/CONTRIBUTOR-ROLES.md#triage-team