### 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> found_renames;
	int current_line = 1;
	for (String &line : lines) {
		if (uint64_t(line.length()) <= maximum_line_length) {
			String old;
			if (line.contains("tool")) {
				old = line;
				line = reg_container.keyword_gdscript_tool.sub(line, "@tool", true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "tool", "@tool", line));
				}
			}
			if (line.contains("export")) {
				old = line;
				line = reg_container.keyword_gdscript_export_single.sub(line, "$1@export", true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "export", "@export", line));
				}
			}
			if (line.contains("export")) {
				old = line;
				line = reg_container.keyword_gdscript_export_mutli.sub(line, "@export", true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "export", "@export", line));
				}
			}
			if (line.contains("onready")) {
				old = line;