Remove reference to a script that was designed for godot v3 and crashed in v4

[TimCabbage]

Instead instructed the user that the desired scaling option is available since version 4.2

[skyace65]

Good change but a few things should be adjusted. I do not think saying that a subviewport was used for this in older Godot versions is necessary. Anyone looking up info for an older Godot version should be using the older version of the docs.

Additionally I don't think this info should be in a note since it's as necessary as what's in the bullet points above the note. I'd make it a bullet point under the one for "set the stretch aspect to keep..." Something like "Set the scale mode to integer"

When editing a doc PR please keep everything to one commit, if you don't know how to do that we have a guide here.

[mhilbrunner]

We just merged a PR that supersedes this one: #8298, so I'm going to close this one. Thanks for pointing this out and taking the time to contribute :)