LU-13136 dom: check read-on-open buffer presents in reply

LU-13136 dom: check read-on-open buffer presents in reply

The ll_dom_finish_open() uses req_capsule_has_field() wronly,
it check only format but not buffer presence in reply, that
causes unneeded console errors about missing buffer later in
req_capsule_server_get()

Patch replaces that with req_capsule_field_present() to check
if server pack that field in reply or not and properly skip
responses from an old server.

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: Ia6114879c90e3e6b8c5020c4912e988cad90df30
Reviewed-on: https://review.whamcloud.com/37249
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Stephane Thiell <sthiell@stanford.edu>