test(sdk): improve KFP SDK local runner test safety #localexecution

[connor-mccarthy]

Description of your changes:
Several changes to improve KFP E2E test safety, organization, and cleanup:

• Always use mode use_venv=True when running E2E tests that use the SubprocessRunner. We should avoid modifying the source under test from within the tests.
• Move component definitions within test methods to ensure dsl.component patch is applied to the component.
• Move tests in e2e_tests.py to subprocess_task_handler_tests.py. Since the DockerRunner behavior is mocked, it doesn't make sense to use these same E2E tests for the DockerRunner. Will add additional DockerRunner tests separately.
• Turn on temporary directory cleanup for E2E tests.

Checklist:

• The title for your pull request (PR) should follow our title convention. Learn more about the pull request title convention used in this repository.

[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

[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
kfp-kubernetes-execution-tests	5142f72	link	false	/test kfp-kubernetes-execution-tests

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[connor-mccarthy]

/assign @chensun

[chensun]

/lgtm
/approve

Thanks!

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chensun

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