Check podGroup CRD for the volcano and the scheudler-plugins as default.

[Syulin7]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #1811

Checklist:

• Docs included if any changes are user facing

[Syulin7]

@johnugeorge @tenzen-y Considering that currently only volcano and scheduler-plugins are supported, when a user enables the gang scheduler, it will automatically check the corresponding CRD and remind the user to install it.

[coveralls]

Pull Request Test Coverage Report for Build 6468588469

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 42.802%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/controller.v1/mpi/mpijob.go	1	91.06%

Totals
Change from base Build 6447526111:	-0.01%
Covered Lines:	3746
Relevant Lines:	8752

---

💛 - Coveralls

[Syulin7]

@johnugeorge @tenzen-y Thanks for the review! please take a look again.

[johnugeorge]

/lgtm

/assign @tenzen-y

[tenzen-y]

It seems that building pipeline for the example image crashed due to "no space left on device" error.

I will submit the PR to fix the issue. Anyway, this PR looks good. @Syulin7 Thank you!

/lgtm
/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Syulin7, tenzen-y

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