Reject unrunnable jobs submitted to reservations.

This effectively reverts commit 73351553. That commit's message is,

     "Improve support for overlapping advanced reservations.
      Patch from Bill Brophy, Bull."

Jobs submitted to reservations that request more resources than are on a
node will pend forever because of that commit. Reverting that commit
causes those jobs to be immediately rejected. Also, that commit doesn't
appear to "improve support for overlapping advanced reservations" in any
way.

The job is already immediately rejected if it asks for more resources
than are on a node without being submitted to a reservation, or if the
job asks for more nodes than are currently in the reservation. So, this
commit just makes behavior consistent.

Bug 5175.