**Description**

Don't mark dag as `failed` when `UNSTABLE` status received from Jenkins.
It can be done by adding `allow_unstable: bool` or `success_status_values: list` parameter to `JenkinsJobTriggerOperator.__init__`. For now `SUCCESS` status is hardcoded, any other lead to fail.

**Use case / motivation**

I want to restart a job (`retries` parameter) only if I get `FAILED` status. `UNSTABLE` is okay for me and it's no need to restart.

**Are you willing to submit a PR?**

Yes

**Related Issues**

No

airflow/providers/jenkins/operators/jenkins_job_trigger.py
When a 'executable' block appears in the json, it means the job execution started
        and the field 'number' then contains the build number.
        :param location: Location to poll, returned in the header of the build_job call
        :param jenkins_server: The jenkins server to poll
        :return: The build_number corresponding to the triggered job
        """
        try_count = 0
        location += '/api/json'
        
        
        self.log.info('Polling jenkins queue at the url %s', location)
        while try_count < self.max_try_before_job_appears:
            location_answer = jenkins_request_with_headers(
                jenkins_server, Request(method='POST', url=location)
            )
            if location_answer is not None:
                json_response = json.loads(location_answer['body'])
                if 'executable' in json_response:
                    build_number = json_response['executable']['number']
                    self.log.info('Job executed on Jenkins side with the build number %s', build_number)
                    return build_number
            try_count += 1
            time.sleep(self.sleep_time)
        raise AirflowException(
            "The job hasn't been executed after polling " f"the queue {self.max_try_before_job_appears} times"
        )
    def get_hook(self) -> JenkinsHook:
        """Instantiate jenkins hook"""
        return JenkinsHook(self.jenkins_connection_id)
    def execute(self, context: Mapping[Any, Any]) -> Optional[str]: