s3: smbd: Ensure all callers to srvstr_pull_req_talloc() pass a zeroed-out dest pointer.

s3: smbd: Ensure all callers to srvstr_pull_req_talloc() pass a zeroed-out dest pointer.

Now we've fixed srvstr_pull_req_talloc() this isn't
strictly needed, but ensuring pointers are initialized
is best practice to avoid future bugs.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15420

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Mon Aug 14 15:55:43 UTC 2023 on atb-devel-224

(cherry picked from commit 5379b8d557a9a16b81eafb87b60b81debc4bfccb)