Update test-on-cng trigger project and improve caching
What does this MR do and why?
- Update
cng-trigger
variables to skip unnecessary forceful image rebuilds and cache invalidation - Change
cng-mirror
repository for test-on-cng child pipeline. This mirror will be a test bed for various build time improvement changes. Until this mirror exists,test-on-cng
should not be part of development flow
Related to: gitlab-org/quality/quality-engineering/team-tasks#2822, gitlab-org/quality/quality-engineering/team-tasks#2839
Edited by Andrejs Cunskis