Linux: Blender process not stopping on Godot-Exit

### Tested versions

Godot v4.3.stable

### System information

Godot v4.3.stable - KDE neon 6.1 22.04 - X11 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3050 (nvidia; 535.183.01) - AMD Ryzen 5 5500 (12 Threads)

### Issue description

After exiting Godot my Blender process stays alive.
Below a sample output of `ps -ef | grep blender` after exiting Godot.

```
user 840681 1998 0 00:31 ? 00:00:01 /snap/blender/5374/blender --background --python-expr import bpy, sys, threading from xmlrpc.server import SimpleXMLRPCServer req = threading.Condition() res = threading.Condition() info = None export_err = None def xmlrpc_server(): server = SimpleXMLRPCServer(('127.0.0.1', 6011)) server.register_function(export_gltf) server.serve_forever() def export_gltf(opts): with req: global info info = ('export_gltf', opts) req.notify() with res: res.wait() if export_err: raise export_err # Important to return a value to prevent the error 'cannot marshal None unless allow_none is enabled'. return 'BLENDER_GODOT_EXPORT_SUCCESSFUL' if bpy.app.version < (3, 0, 0): print('Blender 3.0 or higher is required.', file=sys.stderr) threading.Thread(target=xmlrpc_server).start() while True: with req: while info is None: req.wait() method, opts = info if method == 'export_gltf': try: export_err = None bpy.ops.wm.open_mainfile(filepath=opts['path']) if opts['unpack_all']: bpy.ops.file.unpack_all(method='USE_LOCAL') bpy.ops.export_scene.gltf(**opts['gltf_options']) except Exception as e: export_err = e info = None with res: res.notify()
```

### Steps to reproduce

* Open Godot Project, which uses Blender imports
* Close Godot and see the process list, i.e. `ps -ef | grep blender`

### Minimal reproduction project (MRP)

-

Reproduce the issue by opening a Godot project that uses Blender imports, closing Godot, and checking `ps -ef | grep blender` as described. Trace the Blender import process lifecycle and shutdown handling; done means the Blender process no longer remains alive after Godot exits.

Written by the indexing model from the issue text.