allocator: Consolidate port update logic

[aaronlehmann]

There are a number of overlapping places where the ports are compared between s.Endpoint and s.Spec.Endpoint, and possibly updated:

• If a service needs allocation, reconcilePortConfigs returns a list of port configs, then serviceAllocatePorts updates the endpoint.
• If the service did not need allocation, portsAllocatedInHostPublishMode checks if host-published ports need to be updated.
• If portsAllocatedInHostPublishMode returned true, then updatePortsInHostPublishMode has similar logic to update these host-published ports. It doesn't reuse any of the code or results from portsAllocatedInHostPublishMode.

I find these different functions confusing, and we've had bugs before when they behaved inconsistently or weren't correct. It's especially problematic because the host-published-port-specific functions have to avoid interfering with ingress ports.

I think there should be a single function that reconciles s.Endpoint.Ports with s.Endpoint.Spec.Ports. If any ingress ports change, these should be deallocated/allocated as necessary. If nothing at all changes, we should skip updating the service in the store.

I think this will be easier to maintain than separate paths for general port allocation and only updating host-published ports.

cc @aboch @yongtang @abhinandanpb

[aaronlehmann]

cc @ijc25

[aaronlehmann]

Note that portsAllocatedInHostPublishMode was renamed to hostPublishPortsNeedUpdate.