Actually test that ScalarValues are the same after round trip serialization

[alamb]

Which issue does this PR close?

re #3531
Closes #.

Rationale for this change

While working on #3531 I noticed the round trip scalar serialization test only tests that no errors are thrown while serializing. It doesn't test that the round tripped value is the same

What changes are included in this PR?

Improve test to validate that the value is the same after roundtrip

Are there any user-facing changes?

No

[ursabot]

Benchmark runs are scheduled for baseline = 4b1e044 and contender = e873423. e873423 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