startop: Change the pattern to find the completion of readahead.

The pattern is shown in logcat and should match the text in iorap.

Test: python app_startup_runner.py  --package com.google.android.GoogleCamera  --readahead fadvise --inodes ../tmp.txt   -d
Bug: 142350683
Change-Id: Ia708ea8d29f4c97126e9e721284a0d346e19573b