Break the dependency between non-persistent user and shortcut users.

Operations performed on non-persistent shortcut user is unnecessarily
waiting for operations on shortcut users. Since they are operating on
different target, the dependency can be safely removed.

Also fixes an issue in ShortcutManagerTest where SetSchemaResponse isn't
mocked properly.

Bug: 183618378
Test: atest ShortcutManagerTest1 ShortcutManagerTest2
    ShortcutManagerTest3 ShortcutManagerTest4 ShortcutManagerTest5
    ShortcutManagerTest6 ShortcutManagerTest7 ShortcutManagerTest8
    ShortcutManagerTest9 ShortcutManagerTest10 ShortcutManagerTest11
    ShortcutManagerTest12
Change-Id: I241bd477c38cc7e5414751835931b195f947772c