Issue opendatahub-io#2081: use install -D for robust file copying (opendatahub-io#2112)

Replace cp command with install -D -m 0644 in datascience Dockerfile
for more reliable file copying that creates missing directories.

- Fixes: opendatahub-io#2081
- Tests: pytest tests/containers/workbenches/jupyterlab/jupyterlab_datascience_test.py
- Validation: test-jupyter-datascience-ubi9-python-3.12 Makefile target
- Coverage: Base image tests validate container build and runtime

Signed-off-by: Pramod Toraskar <pramodtoraskar5@gmail.com>

Author: pramodtoraskar

jupyter/datascience/ubi9-python-3.12/Dockerfile.cpu

@@ -125,7 +125,8 @@ RUN echo "Installing softwares and packages" && \
     # Replace Notebook's launcher, "(ipykernel)" with Python's version 3.x.y \
     sed -i -e "s/Python.*/$(python --version | cut -d '.' -f-2)\",/" /opt/app-root/share/jupyter/kernels/python3/kernel.json && \
     # copy jupyter configuration
-    cp /opt/app-root/bin/utils/jupyter_server_config.py /opt/app-root/etc/jupyter && \
+    install -D -m 0644 /opt/app-root/bin/utils/jupyter_server_config.py \
+      /opt/app-root/etc/jupyter/jupyter_server_config.py && \
     # Disable announcement plugin of jupyterlab \
     jupyter labextension disable "@jupyterlab/apputils-extension:announcements" && \
     # Apply JupyterLab addons \