allow upgrades from previous releases using existing_source
This MR:
- Closes #1527 (closed): addresses two issues related to migrating from 1.1.1
- remove unused
existing_sourcesetting from sylva-units HelmRelease - transition ownership of sylva-core GitRepository to sylva-units Helm release
- remove unused
- Closes #1529 (closed)
Edited by Thomas Morin