Fix mistyped internal Pin on HTTP clients

[marcotc]

The default Datadog::Pin or Datadog::DeprecatedPin created on the Net::HTTP, Faraday and http.rb integrations were erroneously typed as web, while they should have been of http type.

This actually is a non-issue for most users, as the span type eventually gets overwritten with http in all three integrations (Faraday example).

Only users that directly manipulate the Datadog::Pin or Datadog::DeprecatedPin associated with these three integrations are affected. The change from web to http will provide better classification of the spans by the backend, providing proper categorization in our front-end. There are no changes to the data contained in a tracer or to the metrics generated by traces.