MyBS: Avoid lock recursion in certificate check
SUSE::MyBS::new tries to fix up API connection error by setting the SUSE
CA certificate as the SSL trust root.
Check that the error is caused by bad certificate, and don't handle
other errors so that users can see authentication errors correctly.
Also unlock the cookie storage in case the problem is resolved with
using the built-in certificate.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>