Related to #1148
Update `_parse_pr_url` method in `pr_agent/git_providers/bitbucket_server_provider.py` to handle URLs with `/users/`.
* Add logic to check for both `/projects/` and `/users/` in the URL path and process them accordingly.
* Modify the method to raise a `ValueError` if neither `/projects/` nor `/users/` is found in the URL.
* Update the `workspace_slug` to include a `~` prefix if the URL contains `/users/`.
Add test case for URL with `/users/` in `tests/unittest/test_bitbucket_provider.py`.
* Ensure the new test case verifies the correct parsing of URLs with `/users/`.
