### 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)

print_line("Starting conversion.");
	uint64_t conversion_start_time = Time::get_singleton()->get_ticks_msec();
	RegExContainer reg_container = RegExContainer();
	int cached_maximum_line_length = maximum_line_length;
	maximum_line_length = 10000; 
	ERR_FAIL_COND_V_MSG(!test_array_names(), false, "Cannot start converting due to problems with data in arrays.");
	ERR_FAIL_COND_V_MSG(!test_conversion(reg_container), false, "Aborting conversion due to validation tests failing");
	maximum_line_length = cached_maximum_line_length;
	
	
	{
		String converter_text = "; Project was converted by built-in tool to Godot 4.0";
		ERR_FAIL_COND_V_MSG(!FileAccess::exists("project.godot"), false, "Current working directory doesn't contain a \"project.godot\" file for a Godot 3 project.");
		Error err = OK;
		String project_godot_content = FileAccess::get_file_as_string("project.godot", &err);
		ERR_FAIL_COND_V_MSG(err != OK, false, "Unable to read \"project.godot\".");
		ERR_FAIL_COND_V_MSG(project_godot_content.contains(converter_text), false, "Project was already converted with this tool.");
		Ref<FileAccess> file = FileAccess::open("project.godot", FileAccess::WRITE);
		ERR_FAIL_COND_V_MSG(file.is_null(), false, "Unable to open \"project.godot\".");
		file->store_string(converter_text + "\n" + project_godot_content);
	}
	Vector<String> collected_files = check_for_files();
	uint32_t converted_files = 0;
	
	for (int i = 0; i < collected_files.size(); i++) {
		String file_name = collected_files[i];
		Vector<SourceLine> source_lines;