RESTRICT AUTOMERGE Revert "Construct AppsFilter cache on background thread"

Bug: 167396858

This reverts commit b0f1feb0.

Reason for revert: Droidcop: culprit for Bug 167396858.
Verified via forrest L38300000681795599 and through discussion with
the original submitter.

https://android-build.googleplex.com/builds/forrest/run/L38300000681795599

Change-Id: Ia37daaa68aa6ce24716a9f2150a88f000503a002