Not precalculating launcher package in Tapl

It may change (say from 'need to choose' or 'nexus launcher' to
launcher3) during the test execution.

Test: Launcher3:com.android.launcher3.ui.AllAppsIconToHomeTest, fallback recents, TaplTests
Change-Id: I529dd5e28749012731af05edd0adaa4b7d205581
2 files changed