Wipe some fields on service "type" updates

Service has had a problem since forever:

- User creates a service type=LoadBalancer
- We silently allocate them a NodePort
- User changes type to ClusterIP
- We fail the operation because they did not clear NodePort

They never asked for or used the NodePort!

Dual-stack introduced some dependent fields that get auto-wiped on
updates.  This carries it further.

If you squint, you can see Service as a big, messy discriminated union,
with type as the discriminator. Ignoring fields for non-selected
union-modes seems right.

This introduces the potential for an apply loop. Specifically, we will
accept YAML that we did not previously accept. Apply could see the
field in local YAML and not in the server and repeatedly try to patch it
in. But since that YAML is currently an error, it seems like a very low
risk. Almost nobody actually specifies their own NodePort values.

To mitigate this somewhat, we only auto-wipe on updates. The same YAML
would fail to create. This is a little inconsistent. We could
auto-wipe on create, too, at the risk of more potential impact.

To do this properly, we need to know the old and new values, which means
we can not do it in defaulting or conversion. So we do it in strategy.

This change also adds unit tests and updates e2e tests to rely on and
verify this behavior.

pkg/apis/core/v1/zz_generated.conversion.go

@@ -7593,8 +7593,8 @@ func autoConvert_v1_ServiceSpec_To_core_ServiceSpec(in *v1.ServiceSpec, out *cor
 	out.HealthCheckNodePort = in.HealthCheckNodePort
 	out.PublishNotReadyAddresses = in.PublishNotReadyAddresses
 	out.SessionAffinityConfig = (*core.SessionAffinityConfig)(unsafe.Pointer(in.SessionAffinityConfig))
-	out.IPFamilies = *(*[]core.IPFamily)(unsafe.Pointer(&in.IPFamilies))
 	out.TopologyKeys = *(*[]string)(unsafe.Pointer(&in.TopologyKeys))
+	out.IPFamilies = *(*[]core.IPFamily)(unsafe.Pointer(&in.IPFamilies))
 	out.IPFamilyPolicy = (*core.IPFamilyPolicyType)(unsafe.Pointer(in.IPFamilyPolicy))
 	return nil
 }