update x/net/http2 to address few bugs (#11144)

additionally also configure http2 healthcheck
values to quickly detect unstable connections
and let them timeout.

also use single transport for proxying requests

cmd/handler-utils.go

@@ -516,7 +516,7 @@ func proxyRequest(ctx context.Context, w http.ResponseWriter, r *http.Request, e
 	})
 
 	r.URL.Scheme = "http"
-	if globalIsSSL {
+	if globalIsTLS {
 		r.URL.Scheme = "https"
 	}