Add details about project, MR settings, and CI/CD configuration for new Engineering projects

Why is this change being made?

This adds recommendation in the Engineering handbook page for new projects regarding:

• Project settings
• Pipeline settings
• CI/CD configuration

Review app: https://7019-recommended-gitlab-org-ci-config.about.gitlab-review.app/handbook/engineering/index.html#gitlab-repositories

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what

Closes #7019 (closed)