Revert "Let Flux manage Calico and MetalLB"

We have quite a few issues that seems (or are for sure) due to !2255 (merged):

• #1579 (closed) (possibly the same as the issue discussed here)
• #1578 (closed)
• what !2817 (closed) is trying to fix

(many of these issues impact the upgrade from 1.1.1 to main, which wasn't sufficiently tested in !2255 (merged) ; due to me being too optimistic)

For these reasons, it seems reasonable to consider reverting !2255 (merged).

This MR:

• reverts !2255 (merged)
• reverts !2815 (merged) which had been merged as a follow-up fix