* Make sure to delete the namespace generated for the test
Otherwise, it might cause name collisions
upon several subsequent runs of the same tests.
* Be more resilient when trying to delete the namespace/project after each test
Do nothing if the namespace/project no longer exists
* Be more resilient when trying to create the namespace/project before each test
Eventually check the existence of the created namespace/project.
* Rename 'helper#GetProjectName' into 'helper#GenerateProjectName'
This makes the intent clearer.
* Make sure to always delete the random namespace/project created when testing project/namespace deletion