scheduler: run Unreserve if Reserve fails

If a reserve plugin's Reserve method returns an error, there could be
previously allocated resources from successfully completed reserve
plugins that must be unallocated by the corresponding Unreserve
operation. Since Unreserve operations are idempotent, this patch runs
the Unreserve operation of ALL reserve plugins when a Reserve operation
fails.

pkg/scheduler/framework/runtime/framework.go

@@ -788,7 +788,8 @@ func (f *frameworkImpl) runPostBindPlugin(ctx context.Context, pl framework.Post
 // RunReservePluginsReserve runs the Reserve method in the set of configured
 // reserve plugins. If any of these plugins returns an error, it does not
 // continue running the remaining ones and returns the error. In such a case,
-// the pod will not be scheduled.
+// the pod will not be scheduled and the caller will be expected to call
+// RunReservePluginsUnreserve.
 func (f *frameworkImpl) RunReservePluginsReserve(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (status *framework.Status) {
 	startTime := time.Now()
 	defer func() {