Automated cherry pick of #1773: Pin the scheduler-plugins version

[tenzen-y]

What this PR does / why we need it:
Cherry-pick of #1773 on v1.6-release.

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

Checklist:

• Docs included if any changes are user facing

[tenzen-y]

/assign @johnugeorge

[coveralls]

Pull Request Test Coverage Report for Build 4481743301

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.2%) to 39.616%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/controller.v1/mpi/mpijob_controller.go	2	77.07%
pkg/controller.v1/paddlepaddle/paddlepaddle_controller.go	3	53.35%

Totals
Change from base Build 4198039036:	0.2%
Covered Lines:	2743
Relevant Lines:	6924

---

💛 - Coveralls

[johnugeorge]

/lgtm
/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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

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