Refactor current cockpit e2e test in TestCafe to use PO model.

[gbetances089]

Current e2e tests for Cockpit under here do not follow the guidelines of Page Object model.

The goal is to move them into a page object model + reduce/remove duplicated code.

### Tasks
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4335
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4336
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4337
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4338
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4339
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4340
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4357
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4358
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4359
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4367
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4368
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/4369