Style: Consolidate & migrate GDScript .editorconfig

• Moved to test project root so a new `.editorconfig` isn't constantly generated.
• Disable attributes only in the files which use invalid syntax deliberately

Author: Repiteo

modules/gdscript/.editorconfig

@@ -1,8 +1,3 @@
 [*.gd]
-indent_style = tab
 indent_size = 4
-insert_final_newline = true
 trim_trailing_whitespace = true
-
-[*.out]
-insert_final_newline = true

modules/gdscript/tests/scripts/.editorconfig

@@ -0,0 +1,12 @@
+# This file is required to workaround `.editorconfig` autogeneration (see #96845).
+
+# Some tests handle invalid syntax deliberately; exclude relevant attributes.
+
+[parser/features/mixed_indentation_on_blank_lines.gd]
+trim_trailing_whitespace = false
+
+[parser/warnings/empty_file_newline.notest.gd]
+insert_final_newline = false
+
+[parser/warnings/empty_file_newline_comment.notest.gd]
+insert_final_newline = false