Make .editorconfig for group_vars/matrix_servers cleaner

It's the same result as b6d45304b4, but it's done in a cleaner way.

.editorconfig

@@ -15,7 +15,11 @@ trim_trailing_whitespace = true
 #########################
 
 # YAML Files
-[*.{yml,yaml,log.config.j2,yaml.j2,group_vars/matrix_servers}]
+[*.{yml,yaml,log.config.j2,yaml.j2}]
+indent_style = space
+indent_size = 2
+
+[group_vars/matrix_servers]
 indent_style = space
 indent_size = 2