reduce allocations in remote

[korniltsev]

pyroscope-go/upstream/remote/remote.go

Lines 158 to 162 in 8003d94

	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)
	fw, err := writer.CreateFormFile("profile", "profile.pprof")
	if err != nil {

Consider streaming writing to the request or avoid the multipart form if possible