### 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)

int current_line = 1;
	Vector<String> found_renames;
	for (String &line : lines) {
		if (uint64_t(line.length()) <= maximum_line_length) {
			String old_line = line;
			process_gdscript_line(line, reg_container, builtin);
			if (old_line != line) {
				found_renames.append(simple_line_formatter(current_line, old_line, line));
			}
		}
	}
	return found_renames;
}
bool ProjectConverter3To4::contains_function_call(String &line, String function) const {
	// 
	// 
	if (!line.contains(function)) {
		return false;
	}
	int index = line.find(function);
	if (index == 0) {
		return true;
	}
	char32_t previous_char = line.get(index - 1);
	return (previous_char < '0' || previous_char > '9') && (previous_char < 'a' || previous_char > 'z') && (previous_char < 'A' || previous_char > 'Z') && previous_char != '_' && previous_char != '$' && previous_char != '@';
}
, this function should run only on all ".gd" files and also on lines in ".tscn" files which are parts of built-in Scripts.
void ProjectConverter3To4::process_gdscript_line(String &line, const RegExContainer &reg_container, bool builtin) {