Core: Fallback to default queue if no placement rules match

YUNIKORN-1650 added an override for default queue name in the config map to solve for the scenario where the provided placement rule is evaluated before other rules.

Scheduler also adds a default queue if the pod labels or annotations does not define a queue name. Because this happens before the placement rules are evaluated, we end up in the same situation of applications getting placed in the default queue and ignoring all other placement rules.