Add dependency check for `envoy-build-ubuntu` and toolchains

### Description

The build image is often getting out of date, and we have an endemic problem in which one or other of the image/toolchains doesnt get updated

We could fairly trivially add a check to see what the latest build image is and the toolchain versions and raise a ticket to address

Fixing would probably be fairly doable also, so we could potentially raise PRs to fix