Display content loading error inside content area

What does this MR do and why?

Display the content loading error inside the content area.

Screenshots or screen recordings

before

after

How to set up and validate locally

1. This feature is behind a feature flag. Enable :refactor_security_extension to turn this feature on.

echo "Feature.enable(:refactor_security_extension)" | rails c

1. Visit an MR page with Security Scanning

The easiest way to populate data for testing is using this extension https://chrome.google.com/webstore/detail/mokku-mock-api-calls-seam/llflfcikklhgamfmnjkgpdadpmdplmji?hl=en and importing mokku-mocks-22-8-2022.json this json.

Once you have enabled the extension:

1. Open the developer tools
2. Find Mokku tab
3. Click on import
4. Import the file mentioned above
5. Wait until the initial request resolves and the widget displays the number of vulnerabilities found
6. Go back to the Mokku tab
7. Change the status of a request to 5
8. Hit the toggle button as shown in the screencast above

Apply the following patch to force triggering a request:

diff --git a/ee/app/assets/javascripts/vue_merge_request_widget/extensions/security_reports/mr_widget_security_reports.vue b/ee/app/assets/javascripts/vue_merge_request_widget/extensions/security_reports/mr_widget_security_reports.vue
index 04645dddb575..f8103dd413b4 100644
--- a/ee/app/assets/javascripts/vue_merge_request_widget/extensions/security_reports/mr_widget_security_reports.vue
+++ b/ee/app/assets/javascripts/vue_merge_request_widget/extensions/security_reports/mr_widget_security_reports.vue
@@ -98,7 +98,9 @@ export default {
       this.isLoading = value;
     },
 
-    fetchExpandedData() {},
+    fetchExpandedData() {
+      return this.fetchCollapsedData();
+    },
 
     fetchCollapsedData() {
       // TODO: check if gl.mrWidgetData can be safely removed after we migrate to the

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #371586 (closed)