False "two collaborative sessions are accessing the file" messages, issues with saving notebooks and .py files

### Product Version

- [ ] Amazon SageMaker Studio Classic
- [X] Amazon SageMaker Studio
- [ ] Issue is not related to SageMaker Studio

### Issue Description

I'm using a shared JupyterLab environment, and I'm getting the following warning:

There is just one session, there might have been a different, expired one previously. But there's no other browser tab where the notebook is opened. (or any other Sagemaker JupyterLab env). Other users from my team, to whom this env is shared, are not opening it either.

### Expected Behavior

Normal operation without warnings and no problems with saving files. No file corruptions ever.

If there are any shared sessions, and "sharing doesn't work" (as the message says), I would expect a possibility to disconnect the other (imagined) "sessions".

### Observed Behavior

The warning pops up after each opening of a ipynb file or before saving ("discard / overwrite"?).
A few times something unexpected happened, where a large section of the file becomes duplicated (like some failed "merge" of changes).

### Product Category

JupyterLab

### Feedback Category

Reliability and Stability

### Other Details

Version 4.1.6, the shared space / instance was created 26 days ago, ml.r7i.4xlarge

The report identifies Amazon SageMaker Studio, JupyterLab 4.1.6, and shared JupyterLab sessions as the affected entry point. Reproduce by opening an .ipynb file and saving it in the shared environment, then compare the warning and duplicated content behavior. Done means no false warning, normal saves, and no file corruption.

Written by the indexing model from the issue text.