Fix to pass apex package names to ApexManager methods

getApksInApex and getApkInApexInstallError need apex package name as a
argument, but apex module name was passed in some code. This is a change
to fix the incorrect code.

Bug: 317926654
Test: atest FrameworksMockingServicesTests:ApexManagerTest
(cherry picked from https://partner-android-review.googlesource.com/q/commit:ee71b0ab06b1d4941efa873fa80c06aef485ea58)

Change-Id: I3b54cdb0c7d5f80f7425041476b8b11349c1a807