Putting breakpoints in files outside of a Python SAM App causes "pydev debugger: warning: trying to add breakpoint to file that does not exist"

If you debug a Python SAM App, but have breakpoints set on other applications/code within your VS Code workspace folder that isn't in the scope (CodeUri) of the App being debugged, warnings like this appear in the output:

```
Waiting for debugger to attach...
pydev debugger: warning: trying to add breakpoint to file that does not exist: /var/task/C:/code/sam-apps/js-app/hello-world/app.js (will have no effect)
pydev debugger: warning: trying to add breakpoint to file that does not exist: /var/task/C:/code/sam-apps/other-py-app/hello_world/app.py (will have no effect)
...debugger attached
```

We should try to create a "clean" debugging experience for the lambda function that is being debugged locally, without impacting any of the user's other settings (like removing breakpoints)

Acceptance Criteria:
* no warnings about other breakpoints
* user doesn't lose any other breakpoints they may have set

Reproduce local Python SAM debugging in a VS Code workspace containing breakpoints outside the debugged application's CodeUri, then inspect the local Lambda debugging and breakpoint-handling entry points. Done means the debug output has no warnings for unrelated breakpoints while all user breakpoints remain intact.

Written by the indexing model from the issue text.