ARROW-17191: [C++][FlightRPC] Handle inlined slices after concatenation

[lidavidm]

See the JIRA for details, but essentially: data was getting corrupted since allocating a new shared_ptr control block was overwriting the data in a GrpcBuffer. This happened because the data was inlined into the structure, which we weren't properly accounting for. Instead, copy the data into a new buffer in these cases.

I'm not sure why creating a new shared_ptr was overlapping an existing allocation, however.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-17191

[kou]

+1

[ursabot]

Benchmark runs are scheduled for baseline = 75ca3b2 and contender = ef6049a. ef6049a is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Failed ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Failed ⬇️0.99% ⬆️0.0%] test-mac-arm
[Finished ⬇️0.27% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.46% ⬆️0.0%] ursa-thinkcentre-m75q
Buildkite builds:
[Failed] ef6049a2 ec2-t3-xlarge-us-east-2
[Finished] ef6049a2 test-mac-arm
[Finished] ef6049a2 ursa-i9-9960x
[Finished] ef6049a2 ursa-thinkcentre-m75q
[Failed] 75ca3b21 ec2-t3-xlarge-us-east-2
[Failed] 75ca3b21 test-mac-arm
[Finished] 75ca3b21 ursa-i9-9960x
[Finished] 75ca3b21 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