### 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)

if (ignored_lines != 0) {
				reason.append(vformat("    Ignored %d lines, because their length exceeds maximum allowed characters - %d.", ignored_lines, maximum_line_length));
			}
		}
		for (int k = 0; k < reason.size(); k++) {
			print_line(reason[k]);
		}
	}
	print_line(vformat("Conversion ended - all files(%d), converted files: (%d), not converted files: (%d).", collected_files.size(), converted_files, collected_files.size() - converted_files));
	uint64_t conversion_end_time = Time::get_singleton()->get_ticks_msec();
	print_line(vformat("Conversion of all files took %10.3f seconds.", (conversion_end_time - conversion_start_time) / 1000.0));
	return true;
}
bool ProjectConverter3To4::validate_conversion() {
	print_line("Starting checking if project conversion can be done.");
	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 conventer_text = "; Project was converted by built-in tool to Godot 4.0";
		ERR_FAIL_COND_V_MSG(!FileAccess::exists("project.godot"), false, "Current directory doesn't contain any 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, "Failed to read content of \"project.godot\" file.");