[MachineScheduler] Add more debug prints w.r.t hazards and pending SUnits (#134328)

While we already have some detailed debug messages on the candidate
selection process -- which selects a SUnit from the Available queue, we
didn't say much about why a SUnit was _not_ moved from Pending queue to
Available queue in the first place, which is just as important as why we
scheduled a node IMHO. Therefore, I added some debug prints for this
very purpose.

I decide to print these extra messages by default (instead of being
guarded by command line like `-misched-detail-resource-booking`) because
we have been printing some of the hazard remarks, so I thought we might
as well print these new messages -- which are mostly about hazard -- by
default.

0 files changed, 0 insertions, 0 deletions