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

* fix races

* revert unintentional change

* fix test as intended

api4/openGraph.go

@@ -6,7 +6,6 @@ package api4
 import (
 	"net/http"
 
-	l4g "github.com/alecthomas/log4go"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
 )
@@ -16,8 +15,6 @@ const OPEN_GRAPH_METADATA_CACHE_SIZE = 10000
 var openGraphDataCache = utils.NewLru(OPEN_GRAPH_METADATA_CACHE_SIZE)
 
 func (api *API) InitOpenGraph() {
-	l4g.Debug(utils.T("api.opengraph.init.debug"))
-
 	api.BaseRoutes.OpenGraph.Handle("", api.ApiSessionRequired(getOpenGraphMetadata)).Methods("POST")
 }