[MM-27952] Fix some logging related races (#15404)

* Fix some logging races

* Move initLogging after config store initialization

app/server.go

@@ -184,7 +184,6 @@ func NewServer(options ...Option) (*Server, error) {
 		hashSeed:            maphash.MakeSeed(),
 	}
 
-	mlog.Info("Server is initializing...")
 	for _, option := range options {
 		if err := option(s); err != nil {
 			return nil, errors.Wrap(err, "failed to apply option")
@@ -204,6 +203,9 @@ func NewServer(options ...Option) (*Server, error) {
 		mlog.Error(err.Error())
 	}
 
+	// This is called after initLogging() to avoid a race condition.
+	mlog.Info("Server is initializing...")
+
 	// It is important to initialize the hub only after the global logger is set
 	// to avoid race conditions while logging from inside the hub.
 	fakeApp := New(ServerConnector(s))

mlog/testing.go

@@ -35,7 +35,7 @@ func NewTestingLogger(tb testing.TB, writer io.Writer) *Logger {
 		logrLogger:   newLogr(),
 	}
 
-	logWriterCore := zapcore.NewCore(makeEncoder(true), logWriterSync, testingLogger.consoleLevel)
+	logWriterCore := zapcore.NewCore(makeEncoder(true), zapcore.Lock(logWriterSync), testingLogger.consoleLevel)
 
 	testingLogger.zap = zap.New(logWriterCore,
 		zap.AddCaller(),