Modified updateUserNotifyProps to directly update the field (#18097)

* Modified updateUserNotifyProps to directly update the field

The method was only being used during import and it unnecessarily
made multiple queries to the DB.

Changed to a separate query that just updated the props field.

https://community-daily.mattermost.com/plugins/focalboard/workspace/zyoahc9uapdn3xdptac6jb69ic?id=285b80a3-257d-41f6-8cf4-ed80ca9d92e5&v=495cdb4d-c13a-4992-8eb9-80cfee2819a4&c=e4f9a891-85d6-4886-8590-1e327f7f8b8f

```release-note
NONE
```

* invalidating cache

```release-note
NONE
```

store/sqlstore/user_store.go

@@ -226,6 +226,18 @@ func (us SqlUserStore) Update(user *model.User, trustedUpdateData bool) (*model.
 	return &model.UserUpdate{New: user, Old: oldUser}, nil
 }
 
+func (us SqlUserStore) UpdateNotifyProps(userID string, props map[string]string) error {
+	if _, err := us.GetMaster().Exec(`UPDATE Users
+		SET NotifyProps = :NotifyProps
+		WHERE Id = :UserId`, map[string]interface{}{
+		"NotifyProps": model.MapToJson(props),
+		"UserId":      userID}); err != nil {
+		return errors.Wrapf(err, "failed to update User with userId=%s", userID)
+	}
+
+	return nil
+}
+
 func (us SqlUserStore) UpdateLastPictureUpdate(userId string) error {
 	curTime := model.GetMillis()