Update HTTP status codes to modern codes (#18063)

* 2xx/3xx/4xx/5xx -> http.Status...
* http.StatusFound -> http.StatusTemporaryRedirect
* http.StatusMovedPermanently -> http.StatusPermanentRedirect

cmd/web_acme.go

@@ -128,5 +128,5 @@ func runLetsEncryptFallbackHandler(w http.ResponseWriter, r *http.Request) {
 	// URI always contains a leading slash, which would result in a double
 	// slash
 	target := strings.TrimSuffix(setting.AppURL, "/") + r.URL.RequestURI()
-	http.Redirect(w, r, target, http.StatusFound)
+	http.Redirect(w, r, target, http.StatusTemporaryRedirect)
 }