Set Go version of base image to 1.17

[tenzen-y]

What this PR does / why we need it:
Currently, Go version is unmatched between gomod and base image of Dockerfile for training operator. So, this PR upgrade Go version of base image.

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

[coveralls]

Pull Request Test Coverage Report for Build 1488170146

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 24.099%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/controller.v1/mpi/mpijob_controller.go	2	75.31%

Totals
Change from base Build 1486793318:	-0.04%
Covered Lines:	1197
Relevant Lines:	4967

---

💛 - Coveralls

[gaocegege]

/lgtm
/approve

Thanks for your contribution! 🎉 👍

[terrytangyuan]

Thanks!

/lgtm

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [gaocegege,terrytangyuan]

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[tenzen-y]

/retest