Remove executor's dependency on k8s.io/client-go

[adriangonz]

What this PR does / why we need it:

Remove k8s.io/client-go as a direct dependency of the executor by getting rid of the SeldonDeploymentClient. This means that, from now on, the executor will only be able to read SeldonDeployment resources passed explicitly from the environment or as files.

Note that k8s.io/client-go may still be present in the go.sum as a 2nd-level dependency through the operator.

Which issue(s) this PR fixes:

Fixes #2092

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[adriangonz]

/cc @RafalSkolasinski @axsaucedo @cliveseldon

[seldondev]

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[seldondev]

Fri Jul 10 15:29:16 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-2106/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=2

[seldondev]

Fri Jul 10 15:29:36 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-2106/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=1

[adriangonz]

/test integration

[seldondev]

Fri Jul 10 15:34:08 UTC 2020
The logs for [integration] [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-2106/3.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=3

[RafalSkolasinski]

Looks good to me! Nice one.

@agm do we have results of notebooks / integration tests for this one?
Good to merge if confirmed that they're passing (don't see reason they shouldn't).

[axsaucedo]

/test integration
/test notebook

[seldondev]

Mon Jul 13 12:07:25 UTC 2020
The logs for [integration] [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-2106/4.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=4

[axsaucedo]

/test notebooks

[seldondev]

Mon Jul 13 12:22:00 UTC 2020
The logs for [notebooks] [5] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2106/5.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=5

[RafalSkolasinski]

/test integration

[seldondev]

Mon Jul 13 15:02:46 UTC 2020
The logs for [integration] [6] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2106/6.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2106 --build=6

[RafalSkolasinski]

Notebook tests have passed, now waiting for integration tests (there was one failure, hence restart).

[RafalSkolasinski]

Tests passed!
🚀

[RafalSkolasinski]

Merging manually