HttpClient call doesn't use the updated command

Problem/Motivation

The call method dispatches an event (http_client.call_pre_execute) to let other modules interacting with client and command variables. The problem is that when the client executes the command, we are not using the updated version of either client and command variables.

Steps to reproduce

Subscribe to the http_client.call_pre_execute event and modify the client or the command. Nothing will happen.

Proposed resolution

Use the $event->client and $event->command variables instead of $client and $command.

API changes

After this change the "onDataIntegrityCheck" method of the "HttpClientManagerSubscriber" will start working properly again. Please double check nothing changed on your service requests.