Removal of remaining DiGraph Python mentions

[betochimas]

Closes #2005 when merged

[rlratzel]

Overall it looks good so far, and here's some early feedback. The main goal is that the cugraph code should not be using deprecated code, and this PR accomplishes that, but we may want to roll back a few of these other changes to allow users to continue to use the deprecated classes in case they haven't migrated yet, but we can discuss offline..

[codecov-commenter]

Codecov Report

Merging #2049 (6c6c653) into branch-22.04 (2e781c1) will decrease coverage by 0.15%.
The diff coverage is 52.21%.

@@               Coverage Diff                @@
##           branch-22.04    #2049      +/-   ##
================================================
- Coverage         73.26%   73.11%   -0.16%     
================================================
  Files               151      155       +4     
  Lines              9736    10061     +325     
================================================
+ Hits               7133     7356     +223     
- Misses             2603     2705     +102     

Impacted Files	Coverage Δ
python/cugraph/cugraph/components/connectivity.py	95.00% <ø> (ø)
python/cugraph/cugraph/structure/graph_classes.py	78.01% <ø> (ø)
...ure/graph_implementation/simpleDistributedGraph.py	22.85% <0.00%> (-0.17%)	⬇️
python/cugraph/cugraph/tests/dask/test_mg_comms.py	19.60% <0.00%> (ø)
python/cugraph/cugraph/traversal/bfs.py	86.00% <ø> (ø)
python/cugraph/cugraph/traversal/sssp.py	92.23% <ø> (ø)
python/cugraph/cugraph/generators/rmat.py	33.65% <36.36%> (-0.80%)	⬇️
python/cugraph/cugraph/structure/convert_matrix.py	62.01% <47.61%> (-14.66%)	⬇️
python/cugraph/cugraph/utilities/utils.py	70.30% <71.42%> (-0.07%)	⬇️
python/cugraph/cugraph/tests/test_balanced_cut.py	100.00% <100.00%> (ø)
... and 31 more

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[rlratzel]

@gpucibot merge