Update translations with new label

And refactor frontend code. Use isEmpty to avoid prop validation
errors because value is a string and not a boolean.

app/assets/javascripts/integrations/edit/components/dynamic_field.vue

@@ -109,17 +109,7 @@ export default {
       };
     },
     valid() {
-      if (!this.required) {
-        return true;
-      }
-      if (this.model) {
-        return true;
-      }
-      if (!this.validated) {
-        return true;
-      }
-
-      return false;
+      return !this.required || !isEmpty(this.model) || !this.validated;
     },
   },
   created() {

locale/gitlab.pot

@@ -8223,6 +8223,9 @@ msgstr ""
 msgid "Enable header and footer in emails"
 msgstr ""
 
+msgid "Enable integration"
+msgstr ""
+
 msgid "Enable maintenance mode"
 msgstr ""