Convert InternalStorageUiTest to Junit 4

This also allows for access to the underlying userId from
ActivityTestJunit4 and updates the click on the delete dialog to use
the non-soft keyboard closing method.

Bug: 407646510
Test: atest com.android.documentsui.InternalStorageUiTest
Flag: EXEMPT test change
Change-Id: I3a97a40b89ae65e15f0f22ef9954099bab8c8ff5