refactor(ivy): migrate ɵɵ prefix back to Δ (#30362)

Now that issues are resolved with Closure compiler, we can move back to our desired prefix of `Δ`.

PR Close #30362

packages/core/test/bundling/injection/bundle.golden_symbols.json

@@ -195,12 +195,12 @@
     "name": "throwMixedMultiProviderError"
   },
   {
-    "name": "ɵɵdefineInjectable"
+    "name": "ΔdefineInjectable"
   },
   {
-    "name": "ɵɵdefineInjector"
+    "name": "ΔdefineInjector"
   },
   {
-    "name": "ɵɵinject"
+    "name": "Δinject"
   }
 ]

packages/core/test/bundling/injection/usage.ts

@@ -6,17 +6,17 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Injector, ɵcreateInjector as createInjector, ɵɵdefineInjectable, ɵɵdefineInjector} from '@angular/core';
+import {Injector, ɵcreateInjector as createInjector, ΔdefineInjectable, ΔdefineInjector} from '@angular/core';
 
 export class RootService {
-  static ngInjectableDef = ɵɵdefineInjectable({
+  static ngInjectableDef = ΔdefineInjectable({
     providedIn: 'root',
     factory: () => new RootService(),
   });
 }
 
 export class ScopedService {
-  static ngInjectableDef = ɵɵdefineInjectable({
+  static ngInjectableDef = ΔdefineInjectable({
     providedIn: null,
     factory: () => new ScopedService(),
   });
@@ -28,7 +28,7 @@ export class ScopedService {
 }
 
 export class DefinedInjector {
-  static ngInjectorDef = ɵɵdefineInjector({
+  static ngInjectorDef = ΔdefineInjector({
     factory: () => new DefinedInjector(),
     providers: [ScopedService],
   });