Chore: Logging improvements (#44925)

Fixing a couple bugs, adds some tests and hopefully decrease 
lock contention when logging.
Switching from using sync.RWMutex to go-kit SwapLogger.
Fixes bug when creating a new logger from an existing one that 
screwed up the keyvals and/or lost the logger name. 

Ref #44681

pkg/services/login/loginservice/loginservice_test.go

@@ -39,7 +39,7 @@ func Test_syncOrgRoles_doesNotBreakWhenTryingToRemoveLastOrgAdmin(t *testing.T)
 
 func Test_syncOrgRoles_whenTryingToRemoveLastOrgLogsError(t *testing.T) {
 	buf := &bytes.Buffer{}
-	logger.SetLogger(level.NewFilter(log.NewLogfmtLogger(buf), level.AllowInfo()))
+	logger.Swap(level.NewFilter(log.NewLogfmtLogger(buf), level.AllowInfo()))
 
 	user := createSimpleUser()
 	externalUser := createSimpleExternalUser()