Shortcut integration with AppSearch (Part 6)

Removes the limitation on the number of shortcuts. Since the shortcuts
have been moved into AppSearch, it no longer occupies system ram. As a
result we can safely removes the limitaion on the number of shortcuts.

Bug: 151359749
Test: atest ShortcutManagerTest1 ShortcutManagerTest2
ShortcutManagerTest3 ShortcutManagerTest4 ShortcutManagerTest5
ShortcutManagerTest6 ShortcutManagerTest7 ShortcutManagerTest8
ShortcutManagerTest9 ShortcutManagerTest10 ShortcutManagerTest11
Test: atest CtsShortcutManagerTestCases

Change-Id: I7b901b854f08d9aa24d8d223e41b10c7f94925ec