Setting a default `timeout-in-minutes`

There have been discussions before about adding a “default” to the agent (see https://github.com/buildkite/agent/pull/788), but it does not appear this ever landed in a usable state.

My problem is that there are a variety of reasons a build might end up in a non-terminating state, which ties up an agent indefinitely. The way to solve this is to set a timeout (obviously), but if I have to rely on every member of our distributed team to remember to do so on every single step of every build pipeline this is doomed to failure.

I want to be able to set up a reasonable “default timeout”, which then forces anyone with a potentially longer-running step to explicitly declare the intended waiting time.

I don’t need any fancy semantics for this to be workable, I just need a default value that will be used in the absence of an explicit declaration in the pipeline!