Handle the upgrade of sylva-units-operator

Similarly to what is explained in #40 (closed), we'll also have to handle the upgrade of sylva-units operator.

For example, in sylva-projects/sylva-core!5791 (merged) we intent to rely on new status conditions introduced in !396 (merged).

This will work on fresh installations of main, since we'll install an up-to-date version of sylva-units-operator, but this won't be the case while upgrading from previous releases (release-1.5).

We can adopt the same strategy as the one described in #40 (comment 2733146080) to handle the upgrade of the operator.