Doc: based: Remove meaningless comment from sync_our_cib()

The comment was added in 5815c22a. It describes the reason for removing
a particular condition. However, the condition no longer exists (because
it was removed), so the comment doesn't refer to anything in the code.

This comment should have been part of the commit message instead.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>