fix(core): guard the jasmine hooks (#51394)

This commit fixes a regression introduced in #50063

Fixes #51382

PR Close #51394

Author: JeanMeche

packages/core/testing/src/test_hooks.ts

@@ -16,12 +16,16 @@ import {resetFakeAsyncZone} from './fake_async';
 import {TestBedImpl} from './test_bed';
 
 // Reset the test providers and the fake async zone before each test.
-beforeEach(getCleanupHook(false));
+// We keep a guard because somehow this file can make it into a bundle and be executed
+// beforeEach is only defined when executing the tests
+globalThis.beforeEach?.(getCleanupHook(false));
 
 // We provide both a `beforeEach` and `afterEach`, because the updated behavior for
 // tearing down the module is supposed to run after the test so that we can associate
 // teardown errors with the correct test.
-afterEach(getCleanupHook(true));
+// We keep a guard because somehow this file can make it into a bundle and be executed
+// afterEach is only defined when executing the tests
+globalThis.afterEach?.(getCleanupHook(true));
 
 function getCleanupHook(expectedTeardownValue: boolean) {
   return () => {