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/encryption-v1_test.go

@@ -57,8 +57,8 @@ var encryptRequestTests = []struct {
 }
 
 func TestEncryptRequest(t *testing.T) {
-	defer func(flag bool) { globalIsSSL = flag }(globalIsSSL)
-	globalIsSSL = true
+	defer func(flag bool) { globalIsTLS = flag }(globalIsTLS)
+	globalIsTLS = true
 	for i, test := range encryptRequestTests {
 		content := bytes.NewReader(make([]byte, 64))
 		req := &http.Request{Header: http.Header{}}