[9.0] Fix leaky Jest mock that causes the Scout Reporter to not some collect test events (#237837) (#238095)

# Backport

This will backport the following commits from `main` to `9.0`:
- [Fix leaky Jest mock that causes the Scout Reporter to not some
collect test events
(#237837)](#237837)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Cesare de
Cal","email":"cesare.decal@elastic.co"},"sourceCommit":{"committedDate":"2025-10-08T15:45:42Z","message":"Fix
leaky Jest mock that causes the Scout Reporter to not some collect test
events (#237837)\n\nWe noticed we weren't collecting some Scout Reporter
events for the\n`src/cli_encryption_keys/jest.config.js` Jest config (we
were just\ncollecting a single `run-begin` event, nothing more).\n\nUpon
further investigation, we noticed we were
mocking/overwriting\n`fs.writeFileSync` the method that the [Scout
Jest\nreporter](https://github.com/elastic/kibana/blob/main/src/platform/packages/private/kbn-scout-reporting/src/reporting/jest/reporter.ts)\nrelies
on.","sha":"75d57f32a789c5325a5e07ecd9bd9d1632158589","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","backport:all-open","v9.3.0"],"title":"Fix
leaky Jest mock that causes the Scout Reporter to not some collect test
events","number":237837,"url":"https://github.com/elastic/kibana/pull/237837","mergeCommit":{"message":"Fix
leaky Jest mock that causes the Scout Reporter to not some collect test
events (#237837)\n\nWe noticed we weren't collecting some Scout Reporter
events for the\n`src/cli_encryption_keys/jest.config.js` Jest config (we
were just\ncollecting a single `run-begin` event, nothing more).\n\nUpon
further investigation, we noticed we were
mocking/overwriting\n`fs.writeFileSync` the method that the [Scout
Jest\nreporter](https://github.com/elastic/kibana/blob/main/src/platform/packages/private/kbn-scout-reporting/src/reporting/jest/reporter.ts)\nrelies
on.","sha":"75d57f32a789c5325a5e07ecd9bd9d1632158589"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.3.0","branchLabelMappingKey":"^v9.3.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/237837","number":237837,"mergeCommit":{"message":"Fix
leaky Jest mock that causes the Scout Reporter to not some collect test
events (#237837)\n\nWe noticed we weren't collecting some Scout Reporter
events for the\n`src/cli_encryption_keys/jest.config.js` Jest config (we
were just\ncollecting a single `run-begin` event, nothing more).\n\nUpon
further investigation, we noticed we were
mocking/overwriting\n`fs.writeFileSync` the method that the [Scout
Jest\nreporter](https://github.com/elastic/kibana/blob/main/src/platform/packages/private/kbn-scout-reporting/src/reporting/jest/reporter.ts)\nrelies
on.","sha":"75d57f32a789c5325a5e07ecd9bd9d1632158589"}}]}] BACKPORT-->

Co-authored-by: Cesare de Cal <cesare.decal@elastic.co>

Author: kibanamachine

src/cli_encryption_keys/interactive.test.js

@@ -49,9 +49,10 @@ describe('encryption key generation interactive', () => {
       .mockResolvedValueOnce(true);
     jest.spyOn(prompt, 'question').mockResolvedValue('/foo/bar');
     jest.spyOn(crypto, 'randomBytes').mockReturnValue('random-key');
-    fs.writeFileSync = jest.fn();
+    const writeFileSyncSpy = jest.spyOn(fs, 'writeFileSync').mockImplementation(() => {});
     await generate(encryptionConfig, { interactive: true });
-    expect(fs.writeFileSync.mock.calls).toMatchSnapshot();
+    expect(writeFileSyncSpy.mock.calls).toMatchSnapshot();
+    writeFileSyncSpy.mockRestore();
   });
   afterEach(() => {
     jest.restoreAllMocks();