Fix error check that never occurs

[tenzen-y]

What this PR does / why we need it:
Because the result of commonutil.UpdateJobConditions() is always nil, we shouldn't return an error.

follow-up: #1859

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 5624194705

• 25 of 54 (46.3%) changed or added relevant lines in 10 files are covered.
• 9 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.5%) to 40.316%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/controller.v1/mpi/mpijob_controller.go	4	5	80.0%
pkg/controller.v1/common/pod.go	0	3	0.0%
pkg/controller.v1/mxnet/mxjob_controller.go	2	5	40.0%
pkg/controller.v1/pytorch/pytorchjob_controller.go	4	7	57.14%
pkg/controller.v1/common/job.go	0	4	0.0%
pkg/controller.v1/paddlepaddle/paddlepaddle_controller.go	3	7	42.86%
pkg/controller.v1/xgboost/xgboostjob_controller.go	2	7	28.57%
pkg/reconciler.v1/common/job.go	0	6	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/controller.v1/common/job.go	1	6.15%
pkg/controller.v1/common/pod.go	1	2.83%
pkg/reconciler.v1/common/job.go	1	8.64%
pkg/controller.v1/mxnet/mxjob_controller.go	6	61.92%

Totals
Change from base Build 5623533920:	0.5%
Covered Lines:	3859
Relevant Lines:	9572

---

💛 - Coveralls

[mimowo]

LGTM

[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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