[REVIEW] Fix repr and concat of StructColumn

[galipremsagar]

Fixes: #8963

This PR fixes a trivial issue in concat where the assumption was that _with_type_metadata is an in-place operation, but it isn't.

[bdice]

Why are these two types handled the same way? What do they have in common?

Are there other types that might need to be handled here -- and how would developers know to put them here? This may not be something that can be addressed in a code comment, but it seems important to consider. The StructColumn type was seemingly left out from a place it should have been included, until an issue was raised, cause identified, and bug fixed.

[galipremsagar]

This is a common pattern:

cudf/python/cudf/cudf/core/frame.py

Lines 2154 to 2157 in 813ac97

	# TODO: _copy_type_metadata is a common pattern to apply after the
	# roundtrip from libcudf. We should build this into a factory function
	# to increase reusability.
	result._copy_type_metadata(self)

To answer why only these two types are being handled separately is because _reassign_categories predates _with_type_metadata and will likely need a cleanup with some careful benchmarking to eliminate _reassign_categories which are out of the scope of this PR.

[codecov]

Codecov Report

Merging #10042 (7fbf59b) into branch-22.02 (967a333) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-22.02   #10042      +/-   ##
================================================
- Coverage         10.49%   10.41%   -0.08%     
================================================
  Files               119      119              
  Lines             20305    20538     +233     
================================================
+ Hits               2130     2139       +9     
- Misses            18175    18399     +224     

Impacted Files	Coverage Δ
python/custreamz/custreamz/kafka.py	29.16% <0.00%> (-0.63%)	⬇️
python/dask_cudf/dask_cudf/sorting.py	92.66% <0.00%> (-0.25%)	⬇️
python/dask_cudf/dask_cudf/core.py	70.85% <0.00%> (-0.17%)	⬇️
python/cudf/cudf/__init__.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/frame.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/index.py	0.00% <0.00%> (ø)
python/cudf/cudf/io/parquet.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/series.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/utils.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/dtypes.py	0.00% <0.00%> (ø)
... and 21 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b01c846...7fbf59b. Read the comment docs.

[galipremsagar]

rerun tests

[bdice]

I copied the comment from DataFrame._concat to Series._concat and committed that suggestion. LGTM!

[galipremsagar]

@gpucibot merge

[galipremsagar]

@gpucibot merge