When creating the NodePort-type service for an ingresscontroller that
specifies the "NodePortService" endpoint publishing strategy type, include
a "metrics" port with port 1936 so that external load balancers can use the
/healthz/ready endpoint.

This commit fixes bug 1881210.

https://bugzilla.redhat.com/show_bug.cgi?id=1881210

* pkg/operator/controller/ingress/nodeport_service.go
(ensureNodePortService): Pass an argument to desiredNodePortService to tell
it not to add a "metrics" port if the service already exists and omits the
port.
(desiredNodePortService): Add a "wantMetricsPort" parameter.  Add port 1936
to the service's ports spec if wantMetricsPort is true.
* pkg/operator/controller/ingress/nodeport_service_test.go
(TestDesiredNodePortService): Add a test case where wantMetricsPort is
true.  Verify that desiredNodePortService returns the expected service.
(TestNodePortServiceChanged): Update the service used for tests to be
consistent with what desiredNodePortService returns.
* test/e2e/operator_test.go
(TestNodePortServiceEndpointPublishingStrategy): Verify that the operator
creates the NodePort-type service with the expected ports.  Verify that the
operator does not add the "metrics" port if it is is removed from the
service.