Add integration and e2e test for the volcano integration

[tenzen-y]

Both integration and e2e tests for the volcano don't exist, although the mpi-operator has a volcano integration feature. So we should add integration and e2e test for the volcano, similar to scheduler-plugins.

We are looking for contributors that are familiar with volcano.

For scheduler-plugins, we have the following tests:

• integration test https://github.com/kubeflow/mpi-operator/blob/21f326d1d2e5f1beed667da0cc61e1d07158ef0c/test/integration/mpi_job_controller_test.go#L466-L474

• e2e test https://github.com/kubeflow/mpi-operator/blob/21f326d1d2e5f1beed667da0cc61e1d07158ef0c/test/e2e/mpi_job_test.go#L306-L309

/help

[tenzen-y]

@lowang-bh Can you take this issue?

[lowang-bh]

@lowang-bh Can you take this issue?

ok, give me some time.

/assign

[tenzen-y]

@lowang-bh Can you take this issue?

ok, give me some time.

/assign

Thanks! /remove-help