Reduce apk size of test apps in WM CTS

By only keeping necessary libraries. Originally there are
14 apks >=3MB. Now they are ~50KB (-5000+ unused classes).
That also reduces the time of compilation and installation.

Bug: 112837428
Test: atest StartActivityTests

Change-Id: Idff3973da125640ab4e950b3ae7c1d7bad5938a8
13 files changed