[sailfish-browser] Remove login observer after use. Contributes to JB#54080 OMP#JOLLA-102
[sailfish-browser] Remove login observer after use. Contributes to JB#54080 OMP#JOLLA-102

Registering the same observer multiple times causes notifications to be
sent multiple times, so it's important to remove the observer when it's
no longer needed (rather than just leave it added).

sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser