Track If Netty Builder Set Resolver and Properly Use Noop Resolver When Proxying

[alzimmermsft]

Description

Fixes #26559

This PR resolves an issue where proxying clients aren't able to use the no-op resolver. This can result in request failures if the HttpClient is being used in a network where it isn't allowed to access external resources, therefore fails to resolve the address and subsequently fails the request.

Now, the Netty builder tracks whether it added the default resolver (done to resolve another performance issue) and if it had and a proxy is being used it will appropriate configure the no-op resolver.

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[srnagar]

Lgtm