Keep same behavior after initiatingPackageName change

InitiatingPackageName was previously set to null for all shell based
installs but has now been changed to "com.android.shell".

Bug: 265203007
Test: atest AppStoreUtilTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:acab1045f3786f775d0c51ffb50f5ff654fc53d8)
Merged-In: I3b8639c5530782375d0b26c9a65c1662eced5493
Change-Id: I3b8639c5530782375d0b26c9a65c1662eced5493