ARROW-17550: [C++][CI][MinGW] Use system Python for GCS testbench

[kou]

We don't need to use MinGW Python because ARROW-16340 moved cpp/src/arrow/python/ to python/pyarrow/src/.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-17550

[github-actions]

⚠️ Ticket has not been started in JIRA, please click 'Start Progress'.

[kou]

+1

[ursabot]

Benchmark runs are scheduled for baseline = 030042f and contender = b2c3743. b2c3743 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Failed ⬇️0.17% ⬆️0.07%] test-mac-arm
[Failed] ursa-i9-9960x
[Failed] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] b2c3743b ec2-t3-xlarge-us-east-2
[Failed] b2c3743b test-mac-arm
[Failed] b2c3743b ursa-i9-9960x
[Failed] b2c3743b ursa-thinkcentre-m75q
[Finished] 030042f0 ec2-t3-xlarge-us-east-2
[Failed] 030042f0 test-mac-arm
[Failed] 030042f0 ursa-i9-9960x
[Finished] 030042f0 ursa-thinkcentre-m75q
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