Do not retrive app detail if the fragment is exiting.

The exit flag can be set by a variety of things, such as when package is
removed, or package is invalid (hidden mainline module). Loading such
packages changes the internal state of ApplicationsState class (an app
singleton), which leads to inconsistencies later.

Fixes: 130166465
Test: robotest
Change-Id: Ib09240cb694fa16692914a7aa9ce354869615c2d