[Bug]: Javadoc not attached to class in some cases

### Describe the bug

In some cases, the javadoc is not attached to the test class, like in the example source code (`ctClass.getComments()` would then be empty).

Note: if there is a package declaration or the javadoc is indented, it will attach the javadoc to the test class.

### Source code you are trying to analyze/transform

```Java
/**
*
* @author uxxxx
*/
public class Test {}
```

### Source code for your Spoon processing

```Java
import spoon.Launcher;
import spoon.compiler.Environment;
import spoon.processing.Processor;
import spoon.reflect.CtModel;
import spoon.reflect.declaration.CtElement;
import spoon.reflect.declaration.CtType;
import spoon.reflect.visitor.DefaultImportComparator;
import spoon.reflect.visitor.DefaultJavaPrettyPrinter;
import spoon.reflect.visitor.ForceImportProcessor;
import spoon.reflect.visitor.ImportCleaner;
import spoon.reflect.visitor.ImportConflictDetector;
import spoon.reflect.visitor.filter.TypeFilter;
import spoon.support.compiler.VirtualFile;

import java.util.List;

public final class Main {
private Main() {
}

private static CtModel buildModel() {
Launcher launcher = new Launcher();

Environment environment = launcher.getEnvironment();
environment.setPrettyPrinterCreator(() -> new DefaultJavaPrettyPrinter(environment) {
{
// copy-pasted from StandardEnvironment#createPrettyPrinterAutoImport
List> preprocessors = List.of(
// try to import as many types as possible
new ForceImportProcessor(),
// remove unused imports first. Do not add new imports at a time when conflicts are not resolved
new ImportCleaner().setCanAddImports(false),
// solve conflicts, the current imports are relevant too
new ImportConflictDetector(),
// compute final imports
new ImportCleaner().setImportComparator(new DefaultImportComparator())
);
this.setIgnoreImplicit(false);
this.setPreprocessors(preprocessors);
this.setMinimizeRoundBrackets(true);
}
});

environment.setComplianceLevel(21);
environment.setShouldCompile(true);

launcher.addInputResource(new VirtualFile(
"""
/**
*
* @author uxxxx
*/
public class Test {}
""",
"Test"
));

return launcher.buildModel();
}

public static void main(String[] args) {
CtModel ctModel = buildModel();

List> types = ctModel.getElements(new TypeFilter<>(CtType.class));

if (types.size() != 1) {
throw new IllegalStateException("No types found");
}

CtType ctType = types.get(0);
if (ctType.getComments().isEmpty()) {
throw new IllegalStateException("No javadoc found");
}
}
}
```

### Actual output

```Java
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Exception in thread "main" java.lang.IllegalStateException: No javadoc found
at org.example.Main.main(Main.java:75)

Process finished with exit code 1
```

### Expected output

```Java
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

Process finished with exit code 0
```

### Spoon Version

11.1.1-beta-18

### JVM Version

openjdk version "21.0.2" 2024-01-16 LTS OpenJDK Runtime Environment Zulu21.32+17-CA (build 21.0.2+13-LTS) OpenJDK 64-Bit Server VM Zulu21.32+17-CA (build 21.0.2+13-LTS, mixed mode, sharing)

### What operating system are you using?

Windows 11

Run the supplied Main reproducer with the Java source shown in the issue and inspect Spoon's parsing and comment-attachment path for top-level classes. Confirm the behavior for the provided source, including the package and indentation variations mentioned. Done means ctType.getComments() contains the Javadoc for the unindented, package-less class, with regression coverage for the reproduced case.

Written by the indexing model from the issue text.