Make it clear when linux installers are blocked on one particular machine

[sxa]

From release retrospective: https://github.com/adoptium/adoptium/issues/104#issuecomment-1036065992

At the moment if the machines for one platform is unavailable the builds stall in a non-obvious way (I found blueocean was the best place to check what had stalled). It would be much better if we can get earlier identification/notification when this situation occurs so that releasing is not delayed longer than is necessary.

[karianna]

For those watching, linuxNew has been renamed to linux