Initialize timezone to a default state (#8560)

model/user.go

@@ -211,7 +211,7 @@ func (u *User) PreSave() {
 	}
 
 	if u.Timezone == nil {
-		u.Timezone = make(map[string]string)
+		u.Timezone = DefaultUserTimezone()
 	}
 
 	if len(u.Password) > 0 {

model/user_test.go

@@ -39,6 +39,10 @@ func TestUserPreSave(t *testing.T) {
 	if user.Timezone == nil {
 		t.Fatal("Timezone is nil")
 	}
+
+	if user.Timezone["useAutomaticTimezone"] != "true" {
+		t.Fatal("Timezone is not set to default")
+	}
 }
 
 func TestUserPreUpdate(t *testing.T) {