Fix the issue with deleting the "Host" header

[titxue]

#5780

[yu199195]

why delete 'Host' from http header

[titxue]

why delete 'Host' from http header

The original logic ends up removing the ‘Host’ header, which causes any custom ‘Host’ header functionality in the request plugin to fail. My recommendation is to remove the code that deletes ‘Host’ to allow the plugin to function correctly, increasing flexibility without forcing the removal of the ‘Host’ header. Alternatively, this could be made configurable, either in the request setup or the service discovery. In any case, forcing the deletion of ‘Host’ in code is not ideal. Please also refer to the details in my submitted issue for further clarification.