[REVIEW] Use custom conda build directory for ccache integration

[dillon-cullinan]

This changes the conda build directory to be a consistent directory when building packages. The resulting work directory from conda must be moved to a repo specific folder for project flash to work.

[dantegd]

@gpucibot merge

[codecov-io]

Codecov Report

Merging #3658 (704210f) into branch-0.19 (fd9ec89) will decrease coverage by 7.23%.
The diff coverage is 92.64%.

@@               Coverage Diff               @@
##           branch-0.19    #3658      +/-   ##
===============================================
- Coverage        80.70%   73.47%   -7.24%     
===============================================
  Files              227      215      -12     
  Lines            17615    17053     -562     
===============================================
- Hits             14217    12529    -1688     
- Misses            3398     4524    +1126     

Flag	Coverage Δ
dask	?
non-dask	73.47% <92.64%> (+0.55%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
python/cuml/cluster/kmeans.pyx	81.90% <ø> (-10.06%)	⬇️
python/cuml/fil/fil.pyx	92.85% <ø> (+1.02%)	⬆️
python/cuml/neighbors/__init__.py	100.00% <ø> (ø)
python/cuml/preprocessing/encoders.py	95.10% <ø> (+0.02%)	⬆️
python/cuml/common/memory_utils.py	76.82% <50.00%> (-2.29%)	⬇️
python/cuml/neighbors/ann.pyx	90.80% <80.00%> (+29.17%)	⬆️
python/cuml/solvers/qn.pyx	97.20% <85.71%> (-0.43%)	⬇️
python/cuml/linear_model/logistic_regression.pyx	89.16% <88.88%> (+0.20%)	⬆️
...ython/cuml/dask/ensemble/randomforestclassifier.py	30.00% <100.00%> (-26.42%)	⬇️
python/cuml/ensemble/randomforestclassifier.pyx	73.40% <100.00%> (-0.09%)	⬇️
... and 91 more

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