Optimize ENV declarations in clp-package Dockerfile to reduce layers

[coderabbitai]

Context

As discussed in PR #1166 (#1166 (comment)), the ENV declarations in tools/docker-images/clp-package/Dockerfile can be optimized to reduce the number of image layers while maintaining VCS friendliness.

Current Implementation

Currently, the Dockerfile uses separate ENV statements:

ENV CLP_HOME="/opt/clp"
ENV PATH="${CLP_HOME}/bin:${PATH}"
ENV PATH="${CLP_HOME}/sbin:${PATH}"
ENV PYTHONPATH="${CLP_HOME}/lib/python3/site-packages"

Proposed Improvement

Use multi-line ENV syntax to reduce layers:

ENV KEY1=VAL1 \
    KEY2=VAL2

References

• PR: feat(docker): Add container image containing the CLP package, for Docker Compose integration (resolves #1164). #1166
• Comment: feat(docker): Add container image containing the CLP package, for Docker Compose integration (resolves #1164). #1166 (comment)
• Requested by: @junhaoliao