Refactor API tests for v2

- Separated v1 and v2 api tests for workbooks and executions;
- Added more tests scenarios;
- Optimize methods realization for v2 tests.

Change-Id: Ic24383bc7e6c059088e98eeeeab28ae7bda2de6a
Closes-Bug: #1384564
Merge "Refactor API tests for v2"