What are these "test" and "rpcs3_old" folders inside RPCS3 main directory?

"test" folder was only added in recent builds.

"rpcs3_old" folder gets created every time after updating RPCS3 and doesn't get deleted.

If we download a fresh RPCS3 build, there is only the "test" folder inside it, which means that at the very least "rpcs3_old" is a redundant folder that should not be there. Moreover, I tried removing them manually and the emulator seems to work fine which is also indicative of it that they are redundant folders only occupying space.

I would appreciate if someone could explain this.