Hardcoded job.args value in flink-job-cluster helm chart

[abroskin]

• Hardcoded value of job.args configuration (https://github.com/GoogleCloudPlatform/flink-on-k8s-operator/blob/master/helm-chart/flink-job-cluster/templates/flinkjobcluster.yaml#L59)
• savepointsDir, hadoopConfig, gcpConfig configurations are missing