Update optional property check in model utils

The isOptionalProperty function now only checks if a property is not required, removing the isNullable condition. This simplifies the logic for determining optional properties.

npm/ng-packs/packages/schematics/src/utils/model.ts

@@ -190,7 +190,7 @@ export function createRefToImportReducerCreator(params: ModelGeneratorParams) {
 }
 
 function isOptionalProperty(prop: PropertyDef) {
-  return !prop.isRequired && prop.isNullable;
+  return !prop.isRequired;
 }
 
 export function parseBaseTypeWithGenericTypes(type: string): string[] {