Fix prow merge's incompatibility with new synced labels.

[kunmingg]

During label auto-sync, we had a label rename: "do-not-merge/work-in-progress" -> "status/in progress", which might cause prow merge uncompleted PR.
One false positive merge here: kubeflow/community#41 (comment)

To fix it:

1. revert all false merges on affected repos (see affected repo list below)

2. update prow merge rule to listen to label "status/in progress", or revert name change of this label.

Affected repos (might merge PR incomplete):

reporting
examples
community
pytorch-operator
caffe2-operator
experimental-beagle
hp-tuning

Those repos are not affected due to bot user's lack of permission (include our most active repos):

kubeflow
tf-operator
testing
example-seldon
experimental-kvc

[jlewi]

So is the plan to keep the label do-not-merge/work-in-progress ?

[jlewi]

/assign @kunmingg

[jlewi]

I checked kubeflow/testing - it looks like we haven't given write access to the team ci-bots instead we gave direct access to the user k8s-ci-robot. We will need to change that so those other repos are sync'd as well.

But we should wait until issues with the label sync are fixed?

[kunmingg]

Agree, easiest way is keep do-not-merge/work-in-progress label. Will add it back.
I checked recent PRs in the 7 affected repos, haven't found another false merge.
If you noticed any please let me know.

[jlewi]

@kunmingg I think this is fixed right? Can we close it?