Move CI_CONFIG_PATH as a predefined project variable

Problem Statement

#246802 (closed) introduced a predefined project variable CI_PROJECT_CONFIG_PATH. It was soon reported to be similar to an existing pipeline predefined variable CI_CONFIG_PATH.

The purpose of introducing CI_PROJECT_CONFIG_PATH was to be able to use it in evaluating group level pipeline configuration.

Since group level pipeline configurations are included, and only project variables are currently supported (and available) at the time of include section evaluation - the variable CI_CONFIG_PATH will not be available for consumption.

Proposal

• Convert CI_CONFIG_PATH as a predefined project variable.
• Remove CI_PROJECT_CONFIG_PATH variable (check if deprecation is required - the variable was introduced in 13.8)