refactor(core): removed getter and changed to readonly variable (#19117)

PR Close #19117

packages/core/src/di/injection_token.ts

@@ -29,10 +29,10 @@
  * @stable
  */
 export class InjectionToken<T> {
+  /** @internal */
+  readonly ngMetadataName = 'InjectionToken';
+
   constructor(protected _desc: string) {}
 
   toString(): string { return `InjectionToken ${this._desc}`; }
-
-  /** @internal */
-  get ngMetadataName() { return 'InjectionToken'; }
 }