LU-11681 lmv: disable remote file statahead

LU-11681 lmv: disable remote file statahead

Remote file statahead is not supported, because such file needs
two RPCs to fetch both LOOKUP and GETATTR lock, on LOOKUP success
we only know file FID, thus can't prepare an inode correctly.

Disable this to avoid noise messages and confusion.

Update sanity.sh test_60g.

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: Ied99dbce320f678ffd94c461bef9d67e107e673c
Reviewed-on: https://review.whamcloud.com/33930
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>