Remove print_figure overrides in backend subclasses

[QuLogic]

PR Summary

AFAICT, print_figure is only called in savefig, and thus has no relation to backend drawing. We went through a lot of trouble to make savefig self-contained, so if this really had any effect, it would be a bug in it instead. But other backends don't do this override and seem to work fine, so these seem superfluous as well.

After this change, just opening a window in Qt and using the save button did not seem to break anything, nor did running savefig with an interactive window open. I did not test Wx, but given the callers of print_figure, I don't see how it could be different.

Fixes #5234

PR Checklist

Documentation and Tests

• [n/a] Has pytest style unit tests (and pytest passes)
• [n/a] Documentation is sphinx and numpydoc compliant (the docs should build without error).
• [n/a] New plotting related features are documented with examples.

Release Notes

• [n/a] New features are marked with a .. versionadded:: directive in the docstring and documented in doc/users/next_whats_new/
• [n/a] API changes are marked with a .. versionchanged:: directive in the docstring and documented in doc/api/next_api_changes/
• [n/a] Release notes conform with instructions in next_whats_new/README.rst or next_api_changes/README.rst

[tacaswell]

Other option would be to change these to draw_idle, but agree that if this is needed here that is a bug better fixed else where.