Remove VisualBoyAdvance variants

[meithecatte]

Apart from its dubious accuracy, VBA is ripe with dangerous vulnerabilities. Considering that an emulator is usually used to open files downloaded from shady sites, it is not responsible to recommend a program with this security posture.

See also:

• https://github.com/visualboyadvance-m/visualboyadvance-m/issues/784
• https://www.youtube.com/watch?v=mHSWxxK6nA8