update SSL cipher list on wikitech to support PFS

this is the same list of ciphers we use
on the main cluster nginx frontends since
recently (I830bec497338a36f)

also use it for wikitech to support
Forward Secrecy

bug: 53259
Change-Id: I90b99b5070e6f01ab8f9c90621a87823ee6f37bf