Add pylibcudf build dir in build.sh for clean (rapidsai#16648)

This PR adds `pylibcudf` build dir in `build.sh` for `clean` to properly delete the pylibcudf build files and folders.

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

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: rapidsai#16648

build.sh

@@ -54,10 +54,11 @@ KAFKA_LIB_BUILD_DIR=${KAFKA_LIB_BUILD_DIR:=${REPODIR}/cpp/libcudf_kafka/build}
 CUDF_KAFKA_BUILD_DIR=${REPODIR}/python/cudf_kafka/build
 CUDF_BUILD_DIR=${REPODIR}/python/cudf/build
 DASK_CUDF_BUILD_DIR=${REPODIR}/python/dask_cudf/build
+PYLIBCUDF_BUILD_DIR=${REPODIR}/python/pylibcudf/build
 CUSTREAMZ_BUILD_DIR=${REPODIR}/python/custreamz/build
 CUDF_JAR_JAVA_BUILD_DIR="$REPODIR/java/target"
 
-BUILD_DIRS="${LIB_BUILD_DIR} ${CUDF_BUILD_DIR} ${DASK_CUDF_BUILD_DIR} ${KAFKA_LIB_BUILD_DIR} ${CUDF_KAFKA_BUILD_DIR} ${CUSTREAMZ_BUILD_DIR} ${CUDF_JAR_JAVA_BUILD_DIR}"
+BUILD_DIRS="${LIB_BUILD_DIR} ${CUDF_BUILD_DIR} ${DASK_CUDF_BUILD_DIR} ${KAFKA_LIB_BUILD_DIR} ${CUDF_KAFKA_BUILD_DIR} ${CUSTREAMZ_BUILD_DIR} ${CUDF_JAR_JAVA_BUILD_DIR} ${PYLIBCUDF_BUILD_DIR}"
 
 # Set defaults for vars modified by flags to this script
 VERBOSE_FLAG=""