Downstream http requests should use the hostname as a subsegment name

[chanchiem]

Requests, HttpLib, and Aiohttp should all generate subsegments whose name is assigned as the hostname, rather than the full URL path.

Reproduction:

patch_all()
xray_recorder.begin_segment("segment")
requests.get("https://aws.amazon.com/some/url/endpoint")
xray_recorder.end_segment()

observe that the subsegment name is https://aws.amazon.com/some/url/endpoint instead of "aws.amazon.com`