Remove flag check to sanitise keyboard shortcuts provided by apps.

Flag has been rolled out. Flag definition to be removed in a follow up.

Bug: 331180422
Flag: EXEMPT removing com.android.systemui.validate_keyboard_shortcut_helper_icon_uri
Test: Manual
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:4784e90b02b7af2b8284c7d359ef675859156314)
Merged-In: Iaca90a21f6337cdf7b149cf11aa7656cfb3bada4
Change-Id: Iaca90a21f6337cdf7b149cf11aa7656cfb3bada4