[Feature] keep added labels and annotations during Job re-run

[aren92]

Currently, pod template metadata is reset to create new job which delete customized label and annotations added during job creation.
File:

kubernetes/contents/job-run.py

Line 45 in 10fd050

job.spec.template.metadata = None

By default k8s job add below labels for unique identification reference - kubernetes Job :

• 'controller-uid'
• 'job-name'
  so, during job recreate, just delete above labels, and keep other labels and annotations which is added during job create

By below solution, I have recreate job and keeps labels and annotions which is added during job create.

1. backup labels & annotations before setting __'job.spec.template.metadata'__as NULL i.e. 'None'

        labels = copy.copy(job.spec.template.metadata.labels)           #create a copy of existing labels
        annotations = copy.copy(job.spec.template.metadata.annotations) #create a copy of existing annotations

2. delete 'controller-uid' and 'job-name' from old labels

        del labels["controller-uid"]
        del labels["job-name"]

3. create objectMeta using backup labels and annotations

         job.spec.template.metadata = client.V1ObjectMeta(labels=labels,annotations=annotations)

If maintainer and reviewer are okay with above solution, i would like to add above solution here.