Step-into a locked synchronized method blocks the debugger

### Apache NetBeans version

Apache NetBeans 16

### What happened

Not only the debugger is blocked, but it cannot be completely stopped and restart is required.

### How to reproduce

Ensure that there is a lock already on the synchronized method's `this`.

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Linux Mint 20.2 Uma

### JDK

OpenJDK 64-Bit Server VM (build 14.0.1+7, mixed mode, sharing)

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

_No response_

### Are you willing to submit a pull request?

No

### Code of Conduct

Yes

Reproduce the issue on Apache NetBeans 16 with OpenJDK 14 on Linux Mint, ensuring the synchronized method's `this` is already locked. Start by tracing the debugger's step-into handling for synchronized methods. Done means stepping in no longer blocks the debugger and the debugger can be stopped and restarted normally.

Written by the indexing model from the issue text.