Do no persist default card

Whenever we receive slot status from the modem, we change the default
card ID to the card ID of the eUICC with the lowest slot index. This
ensures that if the slot mapping changes, we update the default.

Change-Id: I972750c9a590ea565422af8f85b7c67994ea969a
Fixes: 122528354
Test: manual and UiccControllerTest