[SDK] test: Add e2e test for tune function.

[Electronic-Waste]

What this PR does / why we need it:

• Adds an e2e test in the run_e2e_experiment.py for the tune function.
• Change the error field name from metrics_collector to metrics_collector_spec

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #2383

Checklist:

• Docs included if any changes are user facing

[Electronic-Waste]

PTAL👀 @andreyvelich @johnugeorge @tenzen-y @tariq-hasan

[andreyvelich]

Thanks a lot for doing this @Electronic-Waste!
This should help us to make this API more stable.

[Electronic-Waste]

Now run-e2e-tune-api.py has been added, and the error in CI/CD test is addressed.

Also, I found function verify_experiment_results is used in both the tune API test and the original test. So I move this function to verify.py and import it separately in run-e2e-tune-api.py and run-e2e-experiment.py.

Could you take a look?👀 @andreyvelich

[Electronic-Waste]

@andreyvelich I've added a new workflow file e2e-test-tune-api.yaml to .github/workflows, and also, e2e-test-tune-api.sh to test/e2e/v1beta1/scripts/gh-actions. Now, the test for tune API is separate from other tests.

[andreyvelich]

Overall looks good, thank you @tenzen-y, just a few comments.
/assign @johnugeorge @tenzen-y

[Electronic-Waste]

This PR is also related to my GSoC project.

ref issue: #2340

[Electronic-Waste]

I've removed the time.sleep and refactored the workflow file with template.

PTAL👀 @tenzen-y if you are available.

[andreyvelich]

@tenzen-y Does it look to you on how we separate the template-e2e-test ?

[Electronic-Waste]

@andreyvelich I've modified this PR as you suggested in the last few comments. Could you plz take a look when you are available? Thanks so much!

[andreyvelich]

Thanks a lot for doing this @Electronic-Waste!
It should improve tune API stability.
/lgtm
/approve

[google-oss-prow]

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