Wrap CI script shell variables in quotes to fix local testing.

[bdice]

This is a tiny PR that wraps shell script variables in quotes. This fixes an issue I saw in the upload script when ${BUILD_MODE} was not set during local testing of the CI environment.

[codecov]

Codecov Report

Merging #10018 (af134e2) into branch-22.02 (967a333) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-22.02   #10018      +/-   ##
================================================
- Coverage         10.49%   10.41%   -0.08%     
================================================
  Files               119      119              
  Lines             20305    20480     +175     
================================================
+ Hits               2130     2134       +4     
- Misses            18175    18346     +171     

Impacted Files	Coverage Δ
python/custreamz/custreamz/kafka.py	29.16% <0.00%> (-0.63%)	⬇️
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)
... and 19 more

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[bdice]

@gpucibot merge