otelhttp: Deprecate DefaultClient

instrumentation/net/http/otelhttp/client.go

@@ -11,10 +11,12 @@
 	"strings"
 )
 
+// Deprecated: This will be deleted in the future.
+//
 // DefaultClient is the default Client and is used by Get, Head, Post and PostForm.
 // Please be careful of initialization order - for example, if you change
 // the global propagator, the DefaultClient might still be using the old one.
 var DefaultClient = &http.Client{Transport: NewTransport(http.DefaultTransport)}
 
 // Get is a convenient replacement for http.Get that adds a span around the request.
 func Get(ctx context.Context, targetURL string) (resp *http.Response, err error) {