Remove remaining cases of '@message'

Our elasticSearch cluster previously used '@message', but we have since
moved over to using just 'message'. The rest of the uses of '@message'
were removed in I6fb0aa87a291660df879282e9a7851bbb27e9ac2

Change-Id: I2b5d0f176deddb1b1ab9e831395c3216e927d8bf
Merge "Remove remaining cases of '@message'"