Revert "enforcePhoneAccounts should unregister unresolvable accts"

This reverts commit 01083f3a.

Reason for revert: causes regression in phone account registration b/315117203

Bug: 315117203 (regression)
Bug: 310739126
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:2c081211257094b598915e8059f6de80e4d63719)
Merged-In: I1faea0a313e1dadb66d6d082e0d31294033b56e0
Change-Id: I1faea0a313e1dadb66d6d082e0d31294033b56e0