refactor(angular): remove Config.set() method (#22918)

BREAKING CHANGE: The `Config.set()` method has been removed. See https://ionicframework.com/docs/angular/config for examples on how to set config globally, per-component, and per-platform.

angular/test/test-app/src/app/app.module.ts

@@ -63,7 +63,7 @@ import { AlertComponent } from './alert/alert.component';
     AppRoutingModule,
     FormsModule,
     ReactiveFormsModule,
-    IonicModule.forRoot(),
+    IonicModule.forRoot({ keyboardHeight: 12345 }),
   ],
   entryComponents: [
     ModalExampleComponent,

angular/test/test-app/src/app/providers/providers.component.ts

@@ -69,7 +69,6 @@ export class ProvidersComponent {
 
     // test config
     this.isTesting = config.getBoolean('_testing');
-    config.set('keyboardHeight', 12345);
     this.keyboardHeight = config.getNumber('keyboardHeight');
 
     zone.runOutsideAngular(() => {