[Performance] Improvements to ScanCloseMobs logic (#4534)

* [Performance] Minor improvements to ScanCloseMobs

* Remove timer checks one level up to reduce branching

* Reserve memory in m_close_mobs to avoid frequent re-allocations if not already reserved.

zone/client_process.cpp

@@ -281,7 +281,9 @@ bool Client::Process() {
 			}
 		}
 
-		ScanCloseMobProcess();
+		if (m_scan_close_mobs_timer.Check()) {
+			entity_list.ScanCloseMobs(this);
+		}
 
 		if (RuleB(Inventory, LazyLoadBank)) {
 			// poll once a second to see if we are close to a banker and we haven't loaded the bank yet