Revert "logd: iterator corruption paranoia"

This reverts commit 3614a0c5.

The original commit was added to check if what should be impossible
cases were happening.  In the years after it was added, it doesn't
appear that these cases have happened.  Recent reverts removed the
commits that caused the paranoia in the first place, making these
cases even more impossible.

Test: logging unit tests
Change-Id: I687c4d7876a38485e940f004dbd5ae6a1e15fb4c