Remove UntrustedChecker

This mechanism for untrusted certificates is redundant in Android, as
this is used via TrustManagerImpl in conscrypt, which includes another
blacklist validation in which the list of certificates can be updated
via OTA.

Test: make droid docs
Bug: 29631070
Change-Id: Iccd53bc358fbb420836b2fe17dfc46f2a03b60b7
9 files changed