dynamicproxy - remove DHE ciphers

remove these ciphers:

DHE-RSA-AES128-GCM-SHA256:kEDH+AESGCM

as explained in I39b389b63ae6b8 it was an oversight
to still have them and we likely just copied from the nginx
cluster config

Change-Id: Ib1a716de1483cd482a9e00e4091acf512c5c33dd