[Security Solution][Endpoint] Re enable document signing test (#172154)

## Summary

Re-enable document signing test

**Flaky runner**
-
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/4096
x 100 ( all pass )

### Checklist
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Signed-off-by: Ash <[email protected]>

x-pack/plugins/security_solution/public/management/cypress/e2e/response_actions/document_signing.cy.ts

@@ -22,8 +22,7 @@ import { enableAllPolicyProtections } from '../../tasks/endpoint_policy';
 import { createEndpointHost } from '../../tasks/create_endpoint_host';
 import { deleteAllLoadedEndpointData } from '../../tasks/delete_all_endpoint_data';
 
-// FLAKY: https://github.com/elastic/kibana/issues/170674
-describe.skip('Document signing:', { tags: ['@ess', '@serverless', '@brokenInServerless'] }, () => {
+describe('Document signing:', { tags: ['@ess', '@serverless', '@brokenInServerless'] }, () => {
   let indexedPolicy: IndexedFleetEndpointPolicyResponse;
   let policy: PolicyData;
   let createdHost: CreateAndEnrollEndpointHostResponse;