Fix: scheduler: cl#5301 - respect order constraints when relevant resources are being probed

This fixes violations of order constraints introduced by faf44d811 and
8f76b7821.

Given the typical scenario with an order constraint "A.stop -> B.stop",
if A has been cleaned up and is being reprobed while B is stopping,
B.stop should wait for A.probe to complete. Since the pseudo action
"probe_complete" has been dropped by 8f76b7821, the solution here is to
optionally order "A.probe -> B.stop" as the possible alternative of
"A.stop -> B.stop".

This also addresses the cases where actions of B are other actions
than "stop", including order constraints like "A.stop -> B.start"
implied by anti-colocations.