Set `assumeImmutableResults` in security dashboard

- update apollo client to `assumeImmutableResults` to increase
  performance
- update `updateQuery` for project/group/instane-level security
  dashboard to be consistent and immutable

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

 <script>
+import produce from 'immer';
 import { GlAlert, GlButton, GlIntersectionObserver } from '@gitlab/ui';
 import VulnerabilityList from './vulnerability_list.vue';
 import vulnerabilitiesQuery from '../graphql/group_vulnerabilities.graphql';
@@ -66,10 +67,14 @@ export default {
         this.$apollo.queries.vulnerabilities.fetchMore({
           variables: { after: this.pageInfo.endCursor },
           updateQuery: (previousResult, { fetchMoreResult }) => {
-            fetchMoreResult.group.vulnerabilities.nodes.unshift(
+            const results = produce(fetchMoreResult, draftData => {
+              // eslint-disable-next-line no-param-reassign
+              draftData.group.vulnerabilities.nodes = [
                 ...previousResult.group.vulnerabilities.nodes,
-            );
-            return fetchMoreResult;
+                ...draftData.group.vulnerabilities.nodes,
+              ];
+            });
+            return results;
           },
         });
       }

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

 <script>
+import produce from 'immer';
 import { GlAlert, GlButton, GlIntersectionObserver, GlLoadingIcon } from '@gitlab/ui';
 import { fetchPolicies } from '~/lib/graphql';
 import VulnerabilityList from './vulnerability_list.vue';
@@ -63,8 +64,14 @@ export default {
         this.$apollo.queries.vulnerabilities.fetchMore({
           variables: { after: this.pageInfo.endCursor },
           updateQuery: (previousResult, { fetchMoreResult }) => {
-            fetchMoreResult.vulnerabilities.nodes.unshift(...previousResult.vulnerabilities.nodes);
-            return fetchMoreResult;
+            const results = produce(fetchMoreResult, draftData => {
+              // eslint-disable-next-line no-param-reassign
+              draftData.vulnerabilities.nodes = [
+                ...previousResult.vulnerabilities.nodes,
+                ...draftData.vulnerabilities.nodes,
+              ];
+            });
+            return results;
           },
         });
       }

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

 <script>
+import produce from 'immer';
 import { GlAlert, GlButton, GlIntersectionObserver } from '@gitlab/ui';
 import { __ } from '~/locale';
 import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
@@ -93,12 +94,14 @@ export default {
         this.$apollo.queries.vulnerabilities.fetchMore({
           variables: { after: this.pageInfo.endCursor },
           updateQuery: (previousResult, { fetchMoreResult }) => {
-            const newResult = { ...fetchMoreResult };
-            previousResult.project.vulnerabilities.nodes.push(
-              ...fetchMoreResult.project.vulnerabilities.nodes,
-            );
-            newResult.project.vulnerabilities.nodes = previousResult.project.vulnerabilities.nodes;
-            return newResult;
+            const results = produce(fetchMoreResult, draftData => {
+              // eslint-disable-next-line no-param-reassign
+              draftData.project.vulnerabilities.nodes = [
+                ...previousResult.project.vulnerabilities.nodes,
+                ...draftData.project.vulnerabilities.nodes,
+              ];
+            });
+            return results;
           },
         });
       }

ee/app/assets/javascripts/security_dashboard/graphql/provider.js

@@ -18,6 +18,7 @@ const defaultClient = createDefaultClient(
     cacheConfig: {
       fragmentMatcher,
     },
+    assumeImmutableResults: true,
   },
 );