Reorder the target preparers to install apps before test.

Also remove collection of files that won't be present after the test.

Bug: 302034872
Test: csuite-tradefed run commandAndExit csuite-1p3p-pip-flickers --enable-module-dynamic-download --dynamic-download-args pstash:json-credentials-file=/google/data/ro/teams/app-compatibility/test-resources/config/google.com_mobileharness-0e27cf90c7cb.json --package WMShellFlickerTestsPipApps
Change-Id: I7d06c03c94828d4d70eb3dd3f73da5b8f1365d33