Multiple updates to api tests

1. Removed references to decorators.($func) by importing them directly
2. Imported ddt.data as ddt_data to differentiate it from decorators.data - This change is done inorder to make the api tests **consistent** with ui/cli tests
3. Added pylint disables to make pylint happy for all the files in this commit
Removed the global disable of W0142 as per the previous review suggestions. Adding # pylint:disable=W0142 to Line 46 here makes the line go longer than 79 and flake8 doesnt like it. Otherwise this line needs to broken out in to two which makes it look ugly. If somebody wants to fix this after this PR gets merged, it will be great.