### Godot version

4.0.2.stable

### System information

Ubuntu 22.10

### Issue description

This happens when converting a godot3 project to a godot4 project.
Godot3 source
```gdscript
extends Node2D

export(int) var integer := 2
export(Resource) var resource: Resource = null
```

Result
```gdscript
extends Node2D

@export var integer: int := 2
@export var resource: Resource: Resource = null
```

Expected result
```gdscript
extends Node2D

@export var integer := 2
@export var resource: Resource = null
```

If someone can point to where in the code this might be fixed maybe I can fix it myself, sounds like a good first issue.


### Steps to reproduce

Open the given project (or any project really) and convert it to a godot 4 project

### Minimal reproduction project

[Conversion Tool Typing Problem.zip](https://github.com/godotengine/godot/files/11185334/Conversion.Tool.Typing.Problem.zip)

Vector<String> parts;
	int string_size = line.length();
	int start_part = 0; 
	int parts_counter = 0;
	char32_t previous_character = '\0';
	bool is_inside_string = false; 
	ERR_FAIL_COND_V_MSG(line.count("(") != line.count(")"), parts, vformat("Converter internal bug: substring should have equal number of open and close parentheses in line - \"%s\".", line));
	for (int current_index = 0; current_index < string_size; current_index++) {
		char32_t character = line.get(current_index);
		switch (character) {
			case '(': {
				parts_counter++;
				if (parts_counter == 1 && !is_inside_string) {
					start_part = current_index;
				}
				break;
			};
			case ')': {
				parts_counter--;
				if (parts_counter == 0 && !is_inside_string) {