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 53 and 132 is little tricky. If somebody wants to fix this after this PR gets merged, it will be great.