errors: Handle malformed messages in parse_dbus_error

[gfrmin]

parse_dbus_error assumes the exception message always has the form gerror:dbus_error:message and does an unchecked split(':', 2) unpack. If BlueZ (or a proxy/glib path) ever produces a message with fewer colons, this raises ValueError from inside the error handler itself, masking the original failure.

Wrap the split in try/except and fall back to returning a plain BluezDBusException with the raw message.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[infirit]

The mypy errors are unrelated so feel free to ignore them until we fixed them in main.