Remove python based posgres comparsion integration-test

[alamb]

Which issue does this PR close?

Closes #5011

Rationale for this change

https://github.com/apache/arrow-datafusion/tree/master/integration-tests are now covered by https://github.com/apache/arrow-datafusion/blob/master/datafusion/core/tests/sqllogictests/README.md#running-tests-postgres-compatibility as described in #4462

What changes are included in this PR?

Remove integration-test directory and workflow entry

Are these changes tested?

Yes by CI

Are there any user-facing changes?

No

[alamb]

I plan to leave this open for another day to allow additional time for comments and then will merge it

[ursabot]

Benchmark runs are scheduled for baseline = cb05490 and contender = 3f5b834. 3f5b834 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

[jimexist]

Thank you - less code happier me