[Cilium v1.19] deps: upgrade go.mod dependencies

[nddq]

Summary

Part 1 of the Cilium v1.19 upgrade (#1788).

Updates go.mod and go.sum to upgrade Cilium from v1.18.6 to v1.19.0 and all transitive dependencies. This is the foundation PR — all other PRs in this series depend on it.

Files (2): go.mod, go.sum

Estimated size: ~1,500 lines (mostly go.sum changes)

Parent issue: #1788

[rredziak]

Hello @nddq,

please notice, a few days ago a new vulnerability has been discovered in Google's grpc package:

https://nvd.nist.gov/vuln/detail/CVE-2026-33186

Please bump up the version or even apply the change to current main branch.

TIA.

Kind regards,
RR.