Fixes a needed import that was coming from APM but now isolates thing…

…s better for optimization import builds

## Summary

Adds a single line to work with ts config optimizers. What is happening is that this is relying on an import from here:

```
x-pack/legacy/plugins/apm/public/utils/testHelpers.tsx
```

when really it should be isolated and imported within this file.

Testing is just to go to siem and run these commands:

```ts
cd /projects/kibana
node x-pack/legacy/plugins/siem/scripts/optimize_tsconfig.js
node scripts/type_check.js --project x-pack/tsconfig.json
```

Ensure you don't see any errors.

x-pack/plugins/triggers_actions_ui/public/application/components/health_check.test.tsx

@@ -10,6 +10,7 @@ import { HealthCheck } from './health_check';
 
 import { act } from 'react-dom/test-utils';
 import { httpServiceMock } from '../../../../../../src/core/public/mocks';
+import '@testing-library/jest-dom/extend-expect';
 
 const docLinks = { ELASTIC_WEBSITE_URL: 'elastic.co/', DOC_LINK_VERSION: 'current' };