Remove EditableMesh.CreateMeshPartAsync override because it was delet…

…ed from the API (#1346)

include/customDefinitions.d.ts

@@ -360,7 +360,6 @@ interface EditableMesh extends RBXObject {
 	GetAdjacentVertices(this: EditableMesh, vertexId: number): Array<number>;
 	GetVertices(this: EditableMesh): Array<number>;
 	RaycastLocal(this: EditableMesh, origin: Vector3, direction: Vector3): LuaTuple<[number, Vector3, Vector3]>;
-	CreateMeshPartAsync(this: EditableMesh, initialSize: Vector3, options?: CreateMeshPartAsyncOptions): MeshPart;
 }
 
 interface EmotesPages extends InventoryPages {}