How to deal with no longer supported runtimes (or other components)

In #593 we came across that we now have a node 10 build agent while node 10 itself it goes out of LTS just today.

This means if anything breaks inside of node 10 and we still need to keep the agent buildable we will need to fix node on our own to solve the problem. This may lead to a huge issue regarding maintenance effort, so we should come up with a way how we will handle this in the future - to communicate it and to also be able to act accordingly.

And I assume that this would not just affect node, but potentially also other runtimes.

We could e.g. try to align our releases with the LTS timelines, but I guess due to the ammount of different runtimes this may be a bit tricky.

Or we could always try to have two current LTS ones and state that we only support X's agent as long as X also has LTS. Or even say we may add a new agent with X's newest LTS within a ODS version.

Start with the Node 10 build-agent context and the discussion in #593. The issue names no file, test, or entry point; progress would require defining and documenting a policy for unsupported runtimes and determining what evidence shows that the policy is complete.