Fix drawer title not update to system language

Because operation like copy or move, the drawer tile is set by previous
activity. It will not update when activity recreate cause by system
language update.
Change it only set string id and get string on PickerActivity.

Fix: 140392869
Test: manual
Test: DocumentsUIGooglteTests
Change-Id: Ia502fe4ea61690e0e3d36b8eacb63df1bbee3be5