Remove unused required prop in a component

- fixes console error from a required prop not being passed in
- the prop was added, but never used

ee/app/assets/javascripts/security_dashboard/components/first_class_instance_security_dashboard.vue

@@ -27,10 +27,6 @@ export default {
     DashboardNotConfigured,
   },
   props: {
-    vulnerableProjectsEndpoint: {
-      type: String,
-      required: true,
-    },
     vulnerabilitiesExportEndpoint: {
       type: String,
       required: true,

ee/spec/frontend/security_dashboard/components/first_class_instance_security_dashboard_spec.js

@@ -17,7 +17,6 @@ describe('First Class Instance Dashboard Component', () => {
     $apollo: { queries: { projects: { loading } } },
   });
 
-  const vulnerableProjectsEndpoint = '/vulnerable/projects';
   const vulnerabilitiesExportEndpoint = '/vulnerabilities/exports';
 
   const findInstanceVulnerabilities = () => wrapper.find(FirstClassInstanceVulnerabilities);
@@ -35,7 +34,6 @@ describe('First Class Instance Dashboard Component', () => {
       },
       mocks,
       propsData: {
-        vulnerableProjectsEndpoint,
         vulnerabilitiesExportEndpoint,
       },
       stubs: {