stringify attribute (#38968) (#39392)

fixes: #38873

Signed-off-by: Erik Jan de Wit <erikjan.dewit@gmail.com>
(cherry picked from commit f475646b87)

js/apps/admin-ui/src/clients/credentials/X509.tsx

@@ -14,6 +14,7 @@ export const X509 = () => {
         )}
         label={t("allowRegexComparison")}
         labelIcon={t("allowRegexComparisonHelp")}
+        stringify
       />
       <TextControl
         name={convertAttributeNameToForm("attributes.x509.subjectdn")}