Codefix: Remove this-> from static call to CleaningPool. (#14817)

Don't call unnecessarily.

src/economy.cpp

@@ -1192,7 +1192,7 @@ CargoPayment::CargoPayment(Vehicle *front) :
 
 CargoPayment::~CargoPayment()
 {
-	if (this->CleaningPool()) return;
+	if (CleaningPool()) return;
 
 	this->front->cargo_payment = nullptr;
 

src/roadstop.cpp

@@ -30,8 +30,6 @@ RoadStop::~RoadStop()
 	if (this->status.Test(RoadStopStatusFlag::BaseEntry)) {
 		delete this->entries;
 	}
-
-	if (CleaningPool()) return;
 }
 
 /**

src/story.cpp

@@ -39,10 +39,10 @@ INSTANTIATE_POOL_METHODS(StoryPage)
 
 StoryPage::~StoryPage()
 {
-	if (!this->CleaningPool()) {
-		for (StoryPageElement *spe : StoryPageElement::Iterate()) {
-			if (spe->page == this->index) delete spe;
-		}
+	if (CleaningPool()) return;
+
+	for (StoryPageElement *spe : StoryPageElement::Iterate()) {
+		if (spe->page == this->index) delete spe;
 	}
 }