RESTRICT AUTOMERGE Clear app-provided shortcut icons

When displaying keyboard shortcuts provided by an app, clear
any icon that may have been set (this is only possible via
reflection, and is not a intended for usage outside of the system).

Bug: 331180422
Test: Verify on device
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:dbc02ea629b0ea503b2f1accb062bb5ec249aa58)
Merged-In: If7e291eb2254c3cbec23673c65e7477e6ad45b09
Change-Id: If7e291eb2254c3cbec23673c65e7477e6ad45b09