The 'docker.config.infra_image' would default to an amd64 container.
It is possible to reference the correct image for a platform using
the `runtime.GOARCH` variable, eliminating the need to explicitly set
the `infra_image` on non-amd64 platforms.
Also upgrade to Google's pause container version 3.1 from 3.0, which
includes some enhancements around process management.
Fixes#8926