Revert "Fix unpack job cache issue (#3204)"

[dtfranz]

This reverts commit 47aaa6b.

We previously thought this would:

1. Fix jobs not getting listed due to labeler changes
2. Add the labels to jobs when creating existing jobs then updating instead

Instead we've found that jobs created in 4.14 already meet the requirements to be listed by the labeller and that also updating the jobs in this manner can be detrimental because every field in the pod template is immutable and thus generates lots of errors when the update runs.

We'll need to find out why the jobs aren't getting listed and how to handle that in this case in another way. We think the root cause has something to do with the filtering we do here.

[dinhxuanvu]

Well, for this list call, you should use this func SelectorFromValidatedSet or ValidatedSelectorFromSet here to properly validate and construct the label selector. That should avoid potential bad list call to the apiserver.

On a related note, there is no point to update the pod given the pod is created by the job. The proper flow should be to delete the pod and the job and then recreate the job in case of failed pod or in case of rerunning the job (the job cannot be rereun without recreating).