adbd: Automatically disable verity in adb remount.

Before overlayfs, we supported deduplicated filesystems by undoing
deduplication in recovery. This required an extra reboot cycle, so we
changed "adb remount" to disable verity and boot to recovery in one
command.

After overlayfs, adb remount is still trying to undo deduplication,
which leads to very confusing messages. This patch makes things a bit
clearer. "adb remount" will disable verity, which installs overlayfs.
"adb remount -R" will do the same except automatically reboot.

Bug: N/A
Test: adb remount on dynamic partitions device
Change-Id: Id72f6b9e2297c2f4d5722d5679f6264fe660e631