Set experiment names at a max of 40 characters.

[AydanPirani]

What this PR does / why we need it:
As of now, the suggestion service does not start if the concatenation of algorithm and experiment name are more than 63 characters. The experiment gets created successfully on the dashboard, but never runs. This PR directly rejects all experiments with names longer than 40 characters.

Which issue(s) this PR fixes:
Fixes #2454

Checklist:

• [ X ] Docs included if any changes are user facing

Previous Behavior:
Would successfully allow the experiment to be submitted, and would also create the experiment. However, the suggestion service would crash silently with no error output.

New Behavior:
Throws the following error message:

Error from server: error when creating "../experiments/test.yaml": admission webhook "validator.experiment.katib.kubeflow.org" denied the request: metadata.name: Invalid value: "testveryveryverylargenamefillercharactersmorefillerspaces": name must consist of lower case alphanumeric characters or '-', start with an alphabetic character, and end with an alphanumeric character (e.g. 'my-name', or 'abc-123', regex used for validation is '^[a-z]([-a-z0-9]*[a-z0-9])?)' and may not be larger than 40 characters.

[andreyvelich]

/ok-to-test
/rerun-all

[AydanPirani]

/rerun-all

[Electronic-Waste]

Basically LGTM. Just a few adjustments.

[Electronic-Waste]

Suggested change

	" (e.g. 'my-name', or 'abc-123', regex used for validation is '^[a-z]([-a-z0-9]*[a-z0-9])?)'" +
	" and may not be larger than 40 characters. "
	" (e.g. 'my-name', or 'abc-123', regex used for validation is '^[a-z]([-a-z0-9]*[a-z0-9])?)')," +
	" and may not be longer than 40 characters. "

[andreyvelich]

Hi @AydanPirani, did you get a chance to address @Electronic-Waste comment?
We are planning to release Katib 0.18 next week.

[andreyvelich]

Hi @AydanPirani, we have time until this Wednesday to merge this PR before we cut Katib RC.0.
Do you have enough time to finish it ?

[Electronic-Waste]

Thanks for this @AydanPirani! And I think it's okay to merge it directly since we just need to adjust the message content @andreyvelich. I can create a following PR fixing that.

/lgtm

[Electronic-Waste]

/assign @andreyvelich @tenzen-y

[andreyvelich]

/approve

[google-oss-prow]

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