PYTHON-5705 Improve fallback for PyOpenSSL windows system certs loading

[blink1073]

PYTHON-5705

Changes in this PR

System cert loading on Windows is not supported by PyOpenSSL. This changes widens our fallback logic to handle any errors that occur.

Test Plan

Patch build

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is there test coverage?
• Is any followup work tracked in a JIRA ticket? If so, add link(s).

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Is all relevant documentation (README or docstring) updated?