Minor: Move test data into datafusion/core/tests/data

[alamb]

Which issue does this PR close?

Na

Rationale for this change

This is a cleanup I have wanted to do for a while whenever I look in the datafusion/core/tests directory and see intermixed data and code, which offends my sense of order

$ ls tests/

aggregate_simple.csv         data/                        join_fuzz.rs                 parquet_exec.rs              sql_integration.rs           user_defined_plan.rs
aggregate_simple_pipe.csv    dataframe.rs                 jsons/                       path_partition.rs            sqllogictests/               window_fuzz.rs
capitalized_example.csv      dataframe_functions.rs       memory_limit.rs              provider_filter_pushdown.rs  statistics.rs
config_from_env.rs           decimal_data.csv             merge_fuzz.rs                row.rs                       tpc-ds/
csv/                         empty.csv                    null_cases.csv               simplification.rs            tpcds_planning.rs
custom_sources.rs            example.csv                  order_spill_fuzz.rs          sort_key_cursor.rs           tpch-csv/
customer.csv                 fifo.rs                      parquet/                     sql/                         user_defined_aggregates.rs

🤮

What changes are included in this PR?

Move all .csv data files datafusion/core/tests/data

Are these changes tested?

Covered by existing tests

Are there any user-facing changes?

No

[jackwener]

Mixing code and data is really messy. Cleanup them is very nice !

[jackwener]

I review this PR carefully to ensure no mistake in this PR.
I'm sure that this PR just include move file and correct the path.
Due to avoid accumulate conflict, I prepare to do merge quick.

[ursabot]

Benchmark runs are scheduled for baseline = 71b9bae and contender = 664edea. 664edea 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

[alamb]

Thanks @jackwener