recovery: Puke out an /etc/fstab so stuff like busybox/toybox is happy

 * And disregard special mount flags on purpose because of certain
   dubious packages which "exec busybox mount".

Squashed:
Author: Alessandro Astone <ales.astone@gmail.com>
Date:   2021-03-26 18:02:34 +0100

    roots: Correct mount flags in /etc/fstab

    The logic here got inverted.

    Change-Id: I63c0d77fa17442ae8630015a52c7bf1be66f69f4

Change-Id: I163702c9bd7fca3d40676fd6d8476e8deb13acc0