fn: remove async+sync seperation in resource tracker (#1254)

This simplifies resource tracker. Originally, logically we had
split the cpu/mem into two pools where a 20%
was kept specifically for sync calls to avoid
async calls dominating the system. However, resource
tracker should not handle such call prioritization.
Given the improvements to the evictor, I think
we can get rid of this code in resource tracker
for time being.

api/agent/call.go

@@ -259,7 +259,7 @@ func (a *agent) GetCall(opts ...CallOpt) (Call, error) {
 	}
 
 	mem := c.Memory + uint64(c.TmpFsSize)
-	if !a.resources.IsResourcePossible(mem, c.CPUs, c.Type == models.TypeAsync) {
+	if !a.resources.IsResourcePossible(mem, c.CPUs) {
 		return nil, models.ErrCallResourceTooBig
 	}