Remove deprecated GlobalAccount

[GenosseOtt]

Context

As we have deprecated GlobalAccount some time ago, lets remove completely to keep docs and end user complexity as little as possible

Acceptance criteria

• Remove GlobalAccount ressource completly
• Upgrade path: Ensure user moves GlobalAccount to ProviderConfig
• Remove from all end user guides
• CRD Browser - leave? How to handle? @sdischer-sap

[sdischer-sap]

I would love to do that, but I'am afraid this would break the provider upgrade process if the user still has CRs using it.

So in order to do that we need to verify how the upgrade behaves here and if it can be resolves in a clean way once it failed. If the user would just need to remove all CRs and the upgrade would unblock itself than maybe thats still okay (with proper documentation and announcements of course).

So I would make that one a spike first of all and spend some time on experimenting with an upgrade in that test. Maybe that can be part of #156

Lets discuss in refinement