[BEAM-7598] Do not build Python tar file in run_integration_test.sh

[markflyhigh]

Run script run_integration_test.sh is used by Gradle to execute Python test suite, which are running in parallel in Post/Pre-Commit. Building tar ball depends on shared temporary resources which can cause race condition, so we can't include it in this script. Since we have another Gradle task sdist to build the tar ball, only check SDK_LOCATION existence should be sufficient.

This can fix PostCommit flaky in https://issues.apache.org/jira/browse/BEAM-7598.

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---		---	---
Java
Python		---			---	---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website
Non-portable
Portable	---		---	---

See .test-infra/jenkins/README for trigger phrase, status and link of all Jenkins jobs.

[markflyhigh]

Run Python PostCommit

[markflyhigh]

PTAL @udim

[udim]

Run Python PostCommit

[markflyhigh]

Run Python PostCommit

[markflyhigh]

PTAL @udim

[markflyhigh]

+R: @tvalentyn

[tvalentyn]

Thanks, Mark!

[markflyhigh]

PTAL @tvalentyn

[tvalentyn]

Thanks a lot, @markflyhigh !

[markflyhigh]

The failure job Portable_Python is caused by infra and not related to this change. Python Precommit has good coverage on this script. I'll go ahead and merge it.