Clean up SfcOpenflowUtilsTest and re-enable all tests

Clean up SfcOpenflowUtilsTest and re-enable all tests

nextHopGroupIdArray isn't used, remove it.
(int) random() is always 0 (because of rounding), use the default
Random() constructor.
Drop redundant casts.
static methods are final, drop the redundant final modifier.
All the parameter creation methods are used but untrackable, suppress
the unused warnings.
Remove commented code.
Fix shouldThrowExceptionForCreateSetAction() and re-enable it.

Change-Id: I6b14f161eb3c96d5170030b34bc0c6cd0776cae1
Signed-off-by: Stephen Kitt <[email protected]>