Unload rendering plugin also on Windows

[traversaro]

🦟 Bug fix

I am trying to run the Windows test suite on windows with conda-forge dependencies, and the only failures are:

The following tests FAILED:
         25 - INTEGRATION_gpu_rays_ogre2_gl3plus (Failed)
         35 - INTEGRATION_mesh_ogre_gl3plus (Failed)
         65 - INTEGRATION_thermal_camera_ogre2_gl3plus (Failed)
            - RenderingIface_TEST_ogre2_gl3plus (Failed)

The RenderingIface_TEST_ogre2_gl3plus is fixed by removing this old workaround. I opened this to understand if this breaks something.

Summary

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

[traversaro]

If this works, probably we can close #45 .

[iche033]

looks like the win tests are failing in the same way as before?

[traversaro]

Ah, by the way I missed #1049, were you referring to that or Jenkins? It seems that there indeed there the test can't find the engine.