Span type and span operation name for oauthtrace are generic HTTP

[dhermes]

See

go-sdk/stats/tracing/oauthtrace/tracer.go

Lines 30 to 33 in e7d08d5

	opentracing.Tag{Key: tracing.TagKeySpanType, Value: tracing.SpanTypeHTTP},
	opentracing.StartTime(time.Now().UTC()),
	}
	span, _ := tracing.StartSpanFromContext(ctx, t.tracer, tracing.OperationHTTPRequest, startOptions...)

The span.type=http tag and operationName=http.request in the StartSpanFromContext() don't seem specific enough to OAuth.

The OperationHTTPRequest is used in stats/tracing/oauthtrace, stats/tracing/r2trace and stats/tracing/webtrace (as of e7d08d5) and SpanTypeHTTP is used in stats/tracing/oauthtrace and stats/tracing/r2trace.