Cleaning up unused flag.

This feature was never released, but was meant to speed up the launcher's loading time.
It wasn't released because we ended up simply showing a Loading screen for long launch
times, and the extra complexity of this change was not deemed worth the decreased latency.

Bug: 251502424
Test: Verified that this launcher still loads properly when this flag is removed.
Flag: EXEMPT flag removal
Change-Id: Ice0d8cbdc75ad69e80570d31d45c73f307fbf8b8