fix(sdk): revert premature client changes

[connor-mccarthy]

Description of your changes:
Revert KFP SDK client.py changes from #8403.

Checklist:

• The title for your pull request (PR) should follow our title
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[google-oss-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[connor-mccarthy]

/assign @chensun

[google-oss-prow]

@connor-mccarthy: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
kubeflow-pipeline-e2e-test	416d756	link	true	/test kubeflow-pipeline-e2e-test

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[chensun]

/lgtm
/approve

Thanks!

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chensun

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• sdk/OWNERS [chensun]
• test/OWNERS [chensun]

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[connor-mccarthy]

Manually merging, as the kubeflow-pipeline-e2e-test failure is expected.