$wgEventLoggingFile: emery => vanadium

Have server-generated EventLogging events go to vanadium directly, rather than
bounce off of emery. I confirmed all apaches can reach vanadium using dsh.

Change-Id: Ie8097d64ac964ef9a5f7c1fe72f091e0ef5e39e9
Merge "$wgEventLoggingFile: emery => vanadium"