### 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)

parts.append(line.substr(start_part + 1, current_index - start_part - 1));
					start_part = current_index;
				}
				break;
			};
			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) {
					parts.append(line.substr(start_part, current_index - start_part));
					start_part = current_index;
				}
				break;
			};
			case ',': {
				if (parts_counter == 1 && !is_inside_string) {
					parts.append(line.substr(start_part + 1, current_index - start_part - 1));
					start_part = current_index;
				}
				break;
			};
			case '"': {
				if (previous_character != '\\')
					is_inside_string = !is_inside_string;