CI: use trusted runner for build_ci_deb
This is listed as a requirement [0] to have the package imported automatically to apt-staging, but the package was actually imported correctly even if it was built on a Digital Ocean runner. [1]
- [0] https://wikitech.wikimedia.org/wiki/APT_Staging_repository#Requirements
- [1] https://gitlab.wikimedia.org/repos/cloud/wikireplicas-utils/-/jobs/583760
Bug: T395266