Autopkgtests timing out on unstable (ci.debian.net)

debusine's autopkgtests are failing on most archs due to timeouts.

This is a combination of #1065 (closed) and some other issues:

• https://ci.debian.net/packages/d/debusine/testing/ppc64el//64719061/ :
  • debian/tests/integration-tests-workflow-debian-pipeline.py::IntegrationWorkflowDebianPipelineTests::test_debian_pipeline
  • DebusineCollectorTests.test_count_worker_pool_runtime