Enable nested scrolling for Trusted credentials

The list of trusted root certs cannot be scrolled to the end. This is
caused by the disabled nested scrolling. To ensure the
CollapsingToolbarLayout works well with the list, the nested scrolling
feature of ListView needs to be enabled.

Bug: 191011957
Test: manual test
Change-Id: Ic7a41377f983e90c85ca304798851112aebcc349