Style: Consolidate & migrate GDScript .editorconfig

[Repiteo]

• Related: [Editor] Add .editorconfig to the projects. #96845

The above PR introduced an issue where running GDScript tests will create a .editorconfig file in modules/gdscript/tests/scripts/. While it could be added as an ignored item in the local .gitignore, the generated file defines root = true, so all other config options would be erroneously discarded.

This fixes the issue by making use of the new intended behavior: a pre-existing .editorconfig. While a blank file would work, it felt much more appropriate to coincide this a minor style cleanup of the .editorconfig files already in the GDScript module. So now, rather than going from 2→3 files, we're going from 2→1, as all the relevant attributes can be safely handled in a single file (only .gd/.out were given attributes, and they're exclusively found in the test project itself).

[AThousandShips]

Can confirm that this prevents that issue, can't speak to the exact contents of the files but this works

[dalexeev]

Note that *.gd files are located not only in modules/gdscript/tests/scripts/, but also in modules/gdscript/editor/script_templates/.

[Repiteo]

Oop, so they are! I'll keep the module root .editorconfig in that case, so this is now effectively migrating the …/scripts/parser/ config to …/scripts/.

[akien-mga]

Thanks!