Handle spec.loadBalancerIP

[sudomateo]

Context

spec.loadBalancerIP is deprecated upstream but still widely used and widely expected to work. Today only the oxide.computer/floating-ip annotation selects an explicit IP; the field is silently ignored.

Scope

Either:

• Treat the field as equivalent to the oxide.computer/floating-ip annotation (erroring if both are set and disagree), or
• Reject services that set it, with a clear error pointing at the annotation.

Decision goes in addressAllocatorFromAnnotations / EnsureLoadBalancer (internal/provider/load_balancer.go).

Done when

Setting spec.loadBalancerIP either works or fails loudly — never silently does nothing.

[sudomateo]

Let's reject this as it's an anti pattern and that's what annotations are for.