print tfproxy exit value in ci_build_and_push_images script

[RafalSkolasinski]

What this PR does / why we need it:

Print exit value of build_push_tfproxy function in ci_build_and_push_images script.

Which issue(s) this PR fixes:

Related to #2477 but not sure if it closes it.

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

None

[seldondev]

Wed Sep 23 09:08:26 UTC 2020
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2478/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2478 --build=2

[seldondev]

Wed Sep 23 09:08:42 UTC 2020
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2478/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2478 --build=1

[RafalSkolasinski]

/approve

[seldondev]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RafalSkolasinski

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• OWNERS [RafalSkolasinski]

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[seldondev]

Mon Sep 28 12:22:19 UTC 2020
The logs for [lint] [4] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2478/4.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2478 --build=4

[seldondev]

Mon Sep 28 12:23:00 UTC 2020
The logs for [pr-build] [3] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2478/3.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2478 --build=3