Remove usages of rapids-env-update (#564)

Reference: rapidsai/ops#2766

Replace rapids-env-update with rapids-configure-conda-channels,
rapids-configure-sccache, and rapids-date-string.

Authors:
   - Kyle Edwards (https://github.com/KyleFromNVIDIA)

Approvers:
   - AJ Schmidt (https://github.com/ajschmidt8)

ci/build_python.sh

@@ -3,7 +3,11 @@
 
 set -euo pipefail
 
-source rapids-env-update
+rapids-configure-conda-channels
+
+source rapids-configure-sccache
+
+source rapids-date-string
 
 rapids-print-env