Fix codecov in CI (#10347)

This PR fixes `codecov` reports generation when used with `pytest-xdist`.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)
  - Jordan Jacobelli (https://github.com/Ethyling)
  - Bradley Dice (https://github.com/bdice)
  - Benjamin Zaitlen (https://github.com/quasiben)

URL: #10347

ci/gpu/build.sh

@@ -239,9 +239,10 @@ fi
 # TEST - Run py.test, notebooks
 ################################################################################
 
-cd "$WORKSPACE/python/cudf"
+cd "$WORKSPACE/python/cudf/cudf"
+# It is essential to cd into $WORKSPACE/python/cudf/cudf as `pytest-xdist` + `coverage` seem to work only at this directory level.
 gpuci_logger "Python py.test for cuDF"
-py.test -n 8 --cache-clear --basetemp="$WORKSPACE/cudf-cuda-tmp" --ignore="$WORKSPACE/python/cudf/cudf/benchmarks" --junitxml="$WORKSPACE/junit-cudf.xml" -v --cov-config=.coveragerc --cov=cudf --cov-report=xml:"$WORKSPACE/python/cudf/cudf-coverage.xml" --cov-report term --dist=loadscope cudf
+py.test -n 8 --cache-clear --basetemp="$WORKSPACE/cudf-cuda-tmp" --ignore="$WORKSPACE/python/cudf/cudf/benchmarks" --junitxml="$WORKSPACE/junit-cudf.xml" -v --cov-config="$WORKSPACE/python/cudf/.coveragerc" --cov=cudf --cov-report=xml:"$WORKSPACE/python/cudf/cudf-coverage.xml" --cov-report term --dist=loadscope tests
 
 cd "$WORKSPACE/python/dask_cudf"
 gpuci_logger "Python py.test for dask-cudf"

python/cudf/.coveragerc

@@ -1,4 +1,3 @@
 # Configuration file for Python coverage tests
 [run]
-include = cudf/*
-omit = cudf/tests/*
+source = cudf

python/dask_cudf/.coveragerc

@@ -1,4 +1,3 @@
 # Configuration file for Python coverage tests
 [run]
-include = dask_cudf/*
-omit = dask_cudf/tests/*
+source = dask_cudf