Extend cudf devcontainers to specify jitify2 kernel cache (#15068)

This ensures that inside devcontainers, the helper clean commands will also remvoe the jitify2 cache as it is part of the build directory.

Authors:
  - Robert Maynard (https://github.com/robertmaynard)

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

URL: #15068

.devcontainer/Dockerfile

@@ -33,3 +33,4 @@ ENV SCCACHE_REGION="us-east-2"
 ENV SCCACHE_BUCKET="rapids-sccache-devs"
 ENV VAULT_HOST="https://vault.ops.k8s.rapids.ai"
 ENV HISTFILE="/home/coder/.cache/._bash_history"
+ENV LIBCUDF_KERNEL_CACHE_PATH="/home/coder/cudf/cpp/build/${PYTHON_PACKAGE_MANAGER}/cuda-${CUDA_VERSION}/latest/jitify_cache"