AppGui: remove unnecessary PersistentStore::instance()
AppGui: remove unnecessary PersistentStore::instance()

This is handled by init-shared.cpp in 50e83b113df84564def70af01b782814b4e614a3.

Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui