Add E2E test for gang-scheduling

[ChanYiLin]

We now support the gang-scheduling with using kube-batchd and PodGroup
but we don't have tests for it.

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[gaocegege]

@ChanYiLin Are you interested in this issue?

[ChanYiLin]

Ok I can take it!

[gaocegege]

Thanks!

/assign @ChanYiLin

[ChanYiLin]

Hi @gaocegege here in #1093 I found we are going to have massive change in our tests
should I wait until the change is finished?

[gaocegege]

@ChanYiLin I think we can add it now since I am not sure if we have the bandwidth to migrate to pytest.

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This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.