Resolve "Clean up/fix the benchmark scripts"

Closes #20162 (closed)

Tests can be run as follows:

# all tests
pvpython -m paraview.tests -o /tmp/resultsdir

# specific tests
pvpython -m paraview.tests.verify_eyedomelighting -o /tmp/eyedome.png
pvpython -m paraview.tests.basic_rendering -o /tmp/basic.png

Using -h to get available command line options.