Remove internal from SulfurasTests

Signed-off-by: Igor Popov <igor@igorpopov.io>
Fix OpenCover

Signed-off-by: Igor Popov <igor@igorpopov.io>
Remove duplicate code from BackstagePassesTests

Signed-off-by: Igor Popov <igor@igorpopov.io>
Remove unused method

Signed-off-by: Igor Popov <igor@igorpopov.io>
Remove duplicate code from each class

Signed-off-by: Igor Popov <igor@igorpopov.io>
Move all tests in the same class

Signed-off-by: Igor Popov <igor@igorpopov.io>