MR comment does not trigger build

### Jenkins and plugins versions report

Environment

```text
Jenkins: 2.492.2
OS: Linux - 6.6.97+
Java: 17.0.14 - Eclipse Adoptium (OpenJDK 64-Bit Server VM)
--
...
gitlab-branch-source:718.v40b_5f0e67cd3
...
```

### What Operating System are you using (both controller, and any agents involved in the problem)?

kubernetes linux nodes

### Reproduction steps

1. setup a group with "Trigger build on merge request comment" keeping the default "jenkins rebuild"
2. optionally, tick "Enable triggers by Trusted Members only", with or without this flag the issue still happen
3. create a gitlab project, it appears in jenkins
4. create a new MR, it appear in jenkins
5. add a comment as "jenkins rebuild"

### Expected Results

at point 5, it's expected a new job is triggered.

looking at "Multibranch pipeline events" , MR comment is also not logged there.

### Actual Results

at point 5, a new build is expected to be executed.

optionally, looking at "Multibranch pipeline events" , MR comment should be logged there.

### Anything else?

_No response_

### Are you interested in contributing a fix?

_No response_