FIX: Python testing was saving foo_1.valid.png style files

This causes an issue as CTest looks for foo.valid.png

Change-Id: Ia8e809f20c72ce42a20f08e896cf4550191cff71
Removed use of unrequired variable

Change-Id: Idc13c3dc3221c7a13a42080d9ffed5b2cde054e1
Merge topic 'python_testing_filenames' into master

7c3fc180 Removed use of unrequired variable
877eda98 FIX: Python testing was saving foo_1.valid.png style files