Jira Connect: move click ev listener to created

Addresses reviewer feedback from MR:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/81126

app/assets/javascripts/jira_connect/subscriptions/components/sign_in_oauth_button.vue

@@ -24,7 +24,7 @@ export default {
       canUseCrypto: AccessorUtilities.canUseCrypto(),
     };
   },
-  mounted() {
+  created() {
     window.addEventListener('message', this.handleWindowMessage);
   },
   beforeDestroy() {