LU-11835 mdt: return DOM size on open resend

LU-11835 mdt: return DOM size on open resend

DOM size is returned along with DOM lock always, but it is
not true with open resend.

Patch fixes that issue and adds test case.

Lustre-change: https://review.whamcloud.com/34044
Lustre-commit: bc3ef43d36b51d346f22a4c32214c2945c04dbe5

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I73d43933f781f192e9aa8c6ee388a043dab5bde9
Reviewed-on: https://review.whamcloud.com/40223
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>