fixes BUG 2275

[BradReesWork]

Fixes the bug where "to_pandas_edgelist" ignores output column names

[BradReesWork]

rerun tests

[codecov-commenter]

Codecov Report

Merging #2279 (1bf0af0) into branch-22.06 (38be932) will decrease coverage by 7.03%.
The diff coverage is n/a.

❗ Current head 1bf0af0 differs from pull request most recent head 6f65185. Consider uploading reports for the commit 6f65185 to get more accurate results

@@               Coverage Diff                @@
##           branch-22.06    #2279      +/-   ##
================================================
- Coverage         70.82%   63.78%   -7.04%     
================================================
  Files               170      100      -70     
  Lines             11036     4498    -6538     
================================================
- Hits               7816     2869    -4947     
+ Misses             3220     1629    -1591     

Impacted Files	Coverage Δ
python/cugraph/cugraph/__init__.py	100.00% <ø> (ø)
python/cugraph/cugraph/centrality/__init__.py	100.00% <ø> (ø)
...graph/cugraph/centrality/betweenness_centrality.py	89.65% <ø> (ø)
...on/cugraph/cugraph/centrality/degree_centrality.py	81.81% <ø> (ø)
...thon/cugraph/cugraph/centrality/katz_centrality.py	88.23% <ø> (-1.24%)	⬇️
python/cugraph/cugraph/community/egonet.py	97.36% <ø> (ø)
...ython/cugraph/cugraph/community/ktruss_subgraph.py	88.23% <ø> (+2.94%)	⬆️
python/cugraph/cugraph/community/leiden.py	100.00% <ø> (+7.69%)	⬆️
python/cugraph/cugraph/community/louvain.py	100.00% <ø> (+7.69%)	⬆️
python/cugraph/cugraph/community/triangle_count.py	100.00% <ø> (+11.11%)	⬆️
... and 130 more

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[jnke2016]

Looks good to me

[betochimas]

Observing from the current CI failures in test_convert_matrix.py and test_multigraph.py, some columns need to be renamed after this API change. In multiple tests from test_convert_matrix, the columns of res_pdf could be renamed:
res_pdf = res_pdf.rename(columns={"source": "src", "destination": "dst"})

[jnke2016]

It looks like this small change has some ramification on some tests

[BradReesWork]

the test in test_convert_matrix assume that the returned column names are "src", "dst", and "weight", so the updated function will help ensure that. and I fixed all the calls to DiGraph

[BradReesWork]

@gpucibot merge