Revert "Change input injection security model to require INJECT_..."

Revert "Update WindowInputTests after changing injection permiss..."

Revert "Change input injection security model to require INJECT_..."

Revert submission 17125748-require-inject-events-permission

Reason for revert: b/228203157, b/228194124, b/228583652
Reverted Changes:
Ib0d66eff3:Change input injection security model to require I...
Ief1a2f10c:Update WindowInputTests after changing injection p...
Ie2d8d0c3d:Change input injection security model to require I...

Change-Id: I4e77238f00ccd6379486ba77613430fbf166821c