MNT: use brain_gc fixture in some tests

[GuillaumeFavelier]

This PR adds the brain_gc fixture in remaining 3d viz tests.

Closes #8403

I ran the tests locally using master versions of pyvista and pyvistaqt. Maybe some adjustments are necessary.

[larsoner]

Rather than do this, how about we just have both renderer_interactive and brain_gc call this after their yield steps? Calling it more than once should be fine, and having it in both means we shouldn't need to worry about order.

[GuillaumeFavelier]

Sure, I'll see if this solves the need to the intermediate calls too

[GuillaumeFavelier]

There is indeed a difference between pinned and latest versions.

I'll come back to 908c1d2 when new versions are released. For now, some adjustments are necessary here.

[GuillaumeFavelier]

I'll see if this solves the need to the intermediate calls too

For me, it did the trick locally, thanks 👍

Actually there is another strategy: waiting for a new release of pyvista before merging this. Since it's not high priority, I think we can afford to wait.

[larsoner]

I would

1. combine this PR and WIP: Use latest pyvista #8410
2. make sure latest PyVista and PyVistaQt master are installed on CircleCI and the Travis (and Azure) pip pre runs
3. triage the brain_gc to only check if new enough PyVista and PyVistaQt are installed

There is a a slight problem, though, that PyVista is currently at 0.26.0 for some reason. I'll open a PR to fix this, it's weird.

[larsoner]

Suggested change

	import pyvista
	if LooseVersion(pyvista.__version__) <= LooseVersion('0.26.1'):
	if not check_version('pyvista', '0.26.1'):

[larsoner]

... but things are green so let's just do this later. Thanks @GuillaumeFavelier !