### 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> lines = text.split("\n");
	Vector<SourceLine> source_lines;
	for (String &line : lines) {
		SourceLine source_line;
		source_line.line = line;
		source_line.is_comment = false;
		source_lines.append(source_line);
	}
	return source_lines;
}
bool ProjectConverter3To4::test_conversion_gdscript_builtin(String name, String expected, void (ProjectConverter3To4::*func)(Vector<SourceLine> &, const RegExContainer &, bool), String what, const RegExContainer &reg_container, bool builtin_script) {
	Vector<SourceLine> got = split_lines(name);
	(this->*func)(got, reg_container, builtin_script);
	String got_str = collect_string_from_vector(got);
	ERR_FAIL_COND_V_MSG(expected != got_str, false, vformat("Failed to convert %s \"%s\" to \"%s\", got instead \"%s\"", what, name, expected, got_str));
	return true;
}
bool ProjectConverter3To4::test_conversion_with_regex(String name, String expected, void (ProjectConverter3To4::*func)(Vector<SourceLine> &, const RegExContainer &), String what, const RegExContainer &reg_container) {
	Vector<SourceLine> got = split_lines(name);
	(this->*func)(got, reg_container);
	String got_str = collect_string_from_vector(got);
	ERR_FAIL_COND_V_MSG(expected != got_str, false, vformat("Failed to convert %s \"%s\" to \"%s\", got instead \"%s\"", what, name, expected, got_str));
	return true;
}
bool ProjectConverter3To4::test_conversion_basic(String name, String expected, const char *array[][2], LocalVector<RegEx *> &regex_cache, String what) {