Reduce logging data races, fix MySQL test race condition (#7994)

* fix races

* revert unintentional change

* fix test as intended

wsapi/system.go

@@ -4,14 +4,10 @@
 package wsapi
 
 import (
-	l4g "github.com/alecthomas/log4go"
 	"github.com/mattermost/mattermost-server/model"
-	"github.com/mattermost/mattermost-server/utils"
 )
 
 func (api *API) InitSystem() {
-	l4g.Debug(utils.T("wsapi.system.init.debug"))
-
 	api.Router.Handle("ping", api.ApiWebSocketHandler(ping))
 }