csl: Fix Finagle pushsite for 2.12
csl: Fix Finagle pushsite for 2.12

Change the "2.11" string to "2.12" because we publish 2.12
by default.

RB_ID=898937

spockz/finagle,twitter/finagle,spockz/finagle,luciferous/finagle,koshelev/finagle,spockz/finagle,twitter/finagle,mkhq/finagle,luciferous/finagle,spockz/finagle,spockz/finagle,koshelev/finagle,koshelev/finagle,mkhq/finagle,mkhq/finagle,twitter/finagle,twitter/finagle,luciferous/finagle,koshelev/finagle,koshelev/finagle,mkhq/finagle,twitter/finagle,luciferous/finagle,luciferous/finagle,luciferous/finagle,koshelev/finagle,mkhq/finagle,mkhq/finagle,spockz/finagle