ARROW-16216: [Python][FlightRPC] Fix test_flight.py when Flight is not available

[lidavidm]

No description provided.

[lidavidm]

@github-actions crossbow submit python-sdist

[github-actions]

https://issues.apache.org/jira/browse/ARROW-16216

[github-actions]

Revision: 6ff1d84

Submitted crossbow builds: ursacomputing/crossbow @ actions-1868

Task	Status
python-sdist

[kou]

+1

Thanks!

[ursabot]

Benchmark runs are scheduled for baseline = aa641d5 and contender = c50e3fb. c50e3fb 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
[Finished ⬇️0.46% ⬆️0.08%] test-mac-arm
[Failed ⬇️1.13% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.3% ⬆️0.0%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ec2-t3-xlarge-us-east-2/builds/529|c50e3fba ec2-t3-xlarge-us-east-2>
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-test-mac-arm/builds/516|c50e3fba test-mac-arm>
[Failed] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ursa-i9-9960x/builds/515|c50e3fba ursa-i9-9960x>
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ursa-thinkcentre-m75q/builds/526|c50e3fba ursa-thinkcentre-m75q>
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ec2-t3-xlarge-us-east-2/builds/528|aa641d51 ec2-t3-xlarge-us-east-2>
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-test-mac-arm/builds/515|aa641d51 test-mac-arm>
[Failed] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ursa-i9-9960x/builds/514|aa641d51 ursa-i9-9960x>
[Finished] <https://buildkite.com/apache-arrow/arrow-bci-benchmark-on-ursa-thinkcentre-m75q/builds/525|aa641d51 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