TST Install libcudf with mamba

[raydouglass]

DO NOT MERGE

Just testing using mamba install

[bdice]

@raydouglass Oops, I didn't see this PR before opening #9951 - I thought your comment on Slack was about a local test. Apologies for the duplication. We can merge either one if this fixes the problem, but we might prefer gpuci_mamba_retry in #9951 over mamba install in this PR for consistency with the rest of the script which uses gpuci_mamba_retry. cuGraph's adaptation also uses gpuci_mamba_retry: rapidsai/cugraph#1928

[codecov]

Codecov Report

Merging #9949 (b6d8537) into branch-22.02 (967a333) will decrease coverage by 0.08%.
The diff coverage is n/a.

❗ Current head b6d8537 differs from pull request most recent head 6bf052c. Consider uploading reports for the commit 6bf052c to get more accurate results

@@               Coverage Diff                @@
##           branch-22.02    #9949      +/-   ##
================================================
- Coverage         10.49%   10.40%   -0.09%     
================================================
  Files               119      119              
  Lines             20305    20507     +202     
================================================
+ Hits               2130     2134       +4     
- Misses            18175    18373     +198     

Impacted Files	Coverage Δ
python/dask_cudf/dask_cudf/sorting.py	92.30% <0.00%> (-0.61%)	⬇️
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)
python/cudf/cudf/utils/ioutils.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/dataframe.py	0.00% <0.00%> (ø)
... and 14 more

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[raydouglass]

Closing in favor of #9951