[Bug] Some rendering tests ar not doing their job

[bruyeret]

Bug description

These tests should fail or the reference should be updated and the threshold decreased

This succeed as expected but the image have to be updated (I did some changes in this PR #3095 so I know the result is ok) and the threshold decreased

See this test that I added and that seems to work fine:

Steps to reproduce

Run the tests and give a look at the report.

Detailed Behavior

No response

Expected Behavior

Mentionned tests should be updated to fail and the corresponding code should be fixed.

Environment

• vtk.js version: master
• Browsers: any
• OS: any