ARROW-14581: [C++] Fine-grained IPC reader tests are flaky

[westonpace]

The footer contains a copy of the schema. The schema only specifies endianess if the machine is big-endian. So the footer size differs based on the endianess of the test machine.

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on JIRA? https://issues.apache.org/jira/browse/ARROW

Opening JIRAs ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename pull request title in the following format?

ARROW-${JIRA_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - How to contribute patches

[github-actions]

https://issues.apache.org/jira/browse/ARROW-14581

[github-actions]

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

[lidavidm]

Thanks for fixing this.

I'm not sure what's up with the integration tests in CI. It doesn't look related to this.

[ursabot]

Benchmark runs are scheduled for baseline = 48009fb and contender = 55a8b78. 55a8b78 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 ⬇️0.0% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.22% ⬆️0.0%] ursa-thinkcentre-m75q
Supported benchmarks:
ursa-i9-9960x: langs = Python, R, JavaScript
ursa-thinkcentre-m75q: langs = C++, Java
ec2-t3-xlarge-us-east-2: cloud = True