[iOS] [Android] Remove PNSE from some HttpClientHandler methods

[steveisok]

Since HttpClientHandler on mobile can support both the underlying native handler and SocketsHttpHandler, it doesn't make sense to always throw PNSE on some methods due to only the native handler not supporting them.

Fixes #55986

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Issue Details

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Since HttpClientHandler on mobile can support both the underlying native handler and SocketsHttpHandler, it doesn't make sense to always throw PNSE on some methods due to only the native handler not supporting them.

Fixes #55986

Author:	steveisok
Assignees:	-
Labels:	area-System.Net.Http, new-api-needs-documentation
Milestone:	-

[marek-safar]

@akoeplinger was this fix backported?

[steveisok]

@marek-safar It got in before the snap.