Hide dialog checkbox when in kiosk mode

With the new udpated dialog in kiosk mode, the checkbox functionality
doesn't work, so we should just hide it

Bug: 429288575
Test: manual testing
Test: ExternalDisplayDialogDelegateScreenshotTest
Flag: com.android.window.flags.enable_updated_display_connection_dialog
Change-Id: Icc81fdadb518c5fa63040c47c6f5caf6a92738a4