Make sure global and local operators can cohexist

[nicolaferraro]

Don't know if this is needed or can be manager completely within OLM, but if installed manually, two operators (a global and a local one) in a cluster can have issues.

We can add a check that is activated only in global mode, to dynamically blacklist some namespaces if there's already an local operator.

[nicolaferraro]

operator-framework/operator-sdk#2508

[lburgazzoli]

looks like there won't be any solution form the operator-sdk

[nicolaferraro]

Solution reported from them is to use OLM to avoid overlapping configurations. So we do.

[nicolaferraro]

Maybe we can do better, adding a guard ourselves can help. Currently I need an empty cluster if I want to check that global mode works, but this can be avoided with some simple checks in the global operator.