Resolves minor issues in the config drive EC2 metadata tests

* Fixed several instances of "assertIsNotNone( x is not None)"
* Commented out checks for ramdisk and kernel id field values
  due to RM7957. Without a definitive source of truth for where
  these values should come from or if they should be set at all,
  these assertions aren't consistent.

Change-Id: I1d262251b553d57ff98d6fe63af019b33bae8f49
Merge "Resolves minor issues in the config drive EC2 metadata tests"