Minor: consolidate parquet custom_reader integration test into parquet_exec

[alamb]

Which issue does this PR close?

re #3463

Rationale for this change

The easier it is to find existing parquet tests the easier it is to evaluate our coverage

What changes are included in this PR?

I suggest reviewing this PR commit by commit. The

1. The first commit moves the file
2. the second cleans up the test code by removing a #clippy(allow) and an unnecessary level of indent

Are these changes tested?

They are all tests

They are run like:

cargo test  --test parquet_exec

And you can see the output like:

...
test parquet::custom_reader::route_data_access_ops_to_parquet_file_reader_factory ... ok

Are there any user-facing changes?

No tests only

[alamb]

cc @crepererum

[alamb]

@Ted-Jiang or @crepererum I wonder if you would have time to review this PR?

[Ted-Jiang]

LGTM, nice rearrangement.❤️

[crepererum]

thank you

[ursabot]

Benchmark runs are scheduled for baseline = 406c108 and contender = f7201cf. f7201cf 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