Send Keyboard Shortcut broadcasts to current user.

bug: 124526105
Test: After switching to a secondary user: cts-tradefed run cts-dev -m CtsAppTestCases -t android.app.cts.ActivityKeyboardShortcutsTest#testRequestShowKeyboardShortcuts
Change-Id: I033a3bd0f6df7ca939b3aa7c081a6dbf45f1d63f