### 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 (source_line.is_comment) {
					continue;
				}
				String &line = source_line.line;
				if (uint64_t(line.length()) > maximum_line_length) {
					ignored_lines += 1;
				}
			}
		} else {
			reason.append(vformat("    ERROR: File has exceeded the maximum size allowed - %d KB", maximum_file_size / 1024));
			is_ignored = true;
		}
		uint64_t end_time = Time::get_singleton()->get_ticks_msec();
		if (is_ignored) {
			String end_message = vformat("    Checking file took %d ms.", end_time - start_time);
			print_line(end_message);
		} else {
			String file_content_after = collect_string_from_vector(source_lines);
			uint64_t hash_after = file_content_after.hash64();
			
			
			if (hash_before != hash_after || file_name.ends_with(".gdshader")) {
				converted_files++;
				Ref<FileAccess> file = FileAccess::open(file_name, FileAccess::WRITE);
				ERR_CONTINUE_MSG(file.is_null(), vformat("Unable to apply changes to \"%s\", no writing access.", file_name));
				file->store_string(file_content_after);
				reason.append(vformat("    File was changed, conversion took %d ms.", end_time - start_time));
			} else {
				reason.append(vformat("    File was left unchanged, checking took %d ms.", end_time - start_time));
			}