Revert "smbd: add an effective {smb,smbd_smb2}_request->ev_ctx that holds the event...

Revert "smbd: add an effective {smb,smbd_smb2}_request->ev_ctx that holds the event context used for the request processing"

This reverts commit 894e5001c747ce765dad5517778dda55d7d1f4d9.

See the discussion in

https://lists.samba.org/archive/samba-technical/2018-December/131731.html

for the reasoning behind this revert.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>