Fix wrong visibility of link button in a11y tutorial dialog

Root cause: the visibility of link button is not correctly set due to
the onPageSelected callback isn't called when the first page shows

Solution: Manually set the visibility of link button according to the
first tutirial page type when dialog is shown

Bug: 242141428
Test: make RunSettingsRoboTests ROBOTEST_FILTER=AccessibilityGestureNavigationTutorialTest
Change-Id: I33ed07bc7ae39d96baeeed85771c5f13e00ebf44