Fix testGlobalActions_doesntStealImeControl

GlobalActionsDialogTests was not tearing down correctly for lock screen
tests. Calling showOrHideDialog a second time cleans things up.

Fixes: 158580670
Test: atest GlobalActionsDialogTest
Test: atest SystemUITests
Test: atest com.android.systemui.globalactions.GlobalActionsImeTest

Change-Id: I15fbe1ddc4a1c6d0d5c112c2e066e2c964d0e04b