use protocol instead of app protocol for health monitor type

[anvddriesch]

Solves the following bug: https://github.com/vmware/cloud-provider-for-cloud-director/issues/281

Previously, any TCP health monitors defined for a load balancer pool would be removed during an update of the pool which occurs for example during scaling of workers.

The reason is as follows: The TCP type health monitor is added based on the ports Protocol field being TCP when the load balancer pool is first formed as part of load balancer creation here: https://github.com/vmware/cloud-provider-for-cloud-director/blob/2d6e9efaf23df037d4cb1d58484bf04b3f2b8935/pkg/vcdsdk/gateway.go#L1754-L1755 However, in subsequent update cycles we were using the appProtocol field instead of the protocol one: https://github.com/vmware/cloud-provider-for-cloud-director/blob/2d6e9efaf23df037d4cb1d58484bf04b3f2b8935/pkg/ccm/loadbalancer.go#L167 This results in the health check being removed since only TCP type health checks are included in the first place as can be seen here: https://github.com/vmware/cloud-provider-for-cloud-director/blob/2d6e9efaf23df037d4cb1d58484bf04b3f2b8935/pkg/vcdsdk/gateway.go#L751-L752

This PR changes the code to use the ports Protocol also in update cases. The value being changed here is not used in any other functions and deploying this change resulted in health monitors to no longer be removed on update.