Add a convention to make sure experiment_name is parameterized in notebook sample.

[numerology]

Otherwise it's hard for the sample test infra to pick up the pipeline run results after submitting for a run.\

See #2110 .

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This change is 

[numerology]

/test kubeflow-pipeline-e2e-test

[numerology]

/test kubeflow-pipeline-sample-test

[numerology]

/test kubeflow-pipeline-sample-test

[Ark-kun]

/lgtm

If we modify Client so that it can take the default experiment name from an environment variable, then we won't need to explicitly pass the experiment names in the samples.
The Experiment feature does not seem to be used a lot, so the team has added support for "default" experiment.

[numerology]

/lgtm

If we modify Client so that it can take the default experiment name from an environment variable, then we won't need to explicitly pass the experiment names in the samples.
The Experiment feature does not seem to be used a lot, so the team has added support for "default" experiment.

'default' experiment actually sounds sweet. Although there is a caveat: currently the sample test infra assumes that each sample test is running under an experiment where there is only one pipeline run. If we put all runs under the same default experiment, we need to change that logic accordingly.

Thanks for proposing the environment variable approach, that could be convenient, but we need to design a mechanism to make sure the domain of its function. Let's think about it a bit more.

[numerology]

/approve

[gaoning777]

/hold

[gaoning777]

/hold cancel

[gaoning777]

/lgtm
/approve

[k8s-ci-robot]

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[numerology]

/test kubeflow-pipeline-sample-test

[numerology]

/test kubeflow-pipline-sample-test

[numerology]

/test kubeflow-pipeline-sample-test

[numerology]

/test kubeflow-pipeline-sample-test