Draft: PoC for CNG refactoring

What does this MR do?

⚠ ⚠ DO NOT MERGE This is a proof-of-concept ⚠ ⚠

This is a proof-of-concept for different ideas to refactor and improve CNG images and pipelines.

Specific MRs will be forked out of this MR:

• !1306 (closed)

Related issues

Related to:

• gitlab-org/charts/gitlab#4216
• gitlab-org/charts/gitlab#4217
• gitlab-org/charts/gitlab#4218 (moved)
• gitlab-org/charts/gitlab#4219 (moved)
• gitlab-org/charts/gitlab#4220