The github user `openjdk-notifier` is not marked as ignored user in mlbridge bot

[Guoxiong Li]

Hi all,

After integrating SKARA-1119 [1][2], when the developers force-push to the
PR,
the notifier bot will add a comment in the PR by using the github username
`openjdk-notifier`
to notify the developers not to do that again.

But unfortunately, the mlbridge bot doesn't ignore the comments of
`openjdk-notifier`
so that the mlbridge bot will send emails of such comments to the maillist.
An example is listed at [3][4].

It is good to add `openjdk-notifier` to the ignored user list of the
mlbridge bot.
The related code about the configuration in the
`MailingListBridgeBotFactory` is listed below.

```
        var ignoredUsers = specific.get("ignored").get("users").stream()
                                   .map(JSONValue::asString)
```

[1] https://bugs.openjdk.java.net/browse/SKARA-1119
[2]
https://github.com/openjdk/skara/commit/2ba3118357b945cf8b200af412eba3bcb306a615
[3] https://github.com/openjdk/jdk/pull/9049
[4]
https://mail.openjdk.java.net/pipermail/compiler-dev/2022-June/019920.html

Best Regards,
-- Guoxiong