Fix the compliance violations report not showing the merged by avatar

ee/app/assets/javascripts/compliance_dashboard/graphql/mappers.js

+import { convertObjectPropsToSnakeCase } from '~/lib/utils/common_utils';
+
 export const mapViolations = (nodes = []) => {
   return nodes.map((node) => ({
     ...node,
@@ -8,7 +10,7 @@ export const mapViolations = (nodes = []) => {
       participants: node.mergeRequest.participants?.nodes || [],
       // TODO: Once the legacy dashboard is removed (https://gitlab.com/gitlab-org/gitlab/-/issues/346266) we can update the drawer to use the new attributes and remove these 2 mappings
       reference: node.mergeRequest.ref,
-      mergedBy: node.mergeRequest.mergeUser,
+      mergedBy: convertObjectPropsToSnakeCase(node.mergeRequest.mergeUser),
       project: {
         ...node.mergeRequest.project,
         complianceFramework: node.mergeRequest.project?.complianceFrameworks?.nodes[0] || null,

ee/spec/frontend/compliance_dashboard/graphql/mappers_spec.js

 import { mapViolations } from 'ee/compliance_dashboard/graphql/mappers';
+import { convertObjectPropsToSnakeCase } from '~/lib/utils/common_utils';
 import { createComplianceViolation } from '../mock_data';
 
 describe('mapViolations', () => {
@@ -7,7 +8,7 @@ describe('mapViolations', () => {
 
     expect(mergeRequest).toMatchObject({
       reference: mergeRequest.ref,
-      mergedBy: mergeRequest.mergeUser,
+      mergedBy: convertObjectPropsToSnakeCase(mergeRequest.mergeUser),
     });
   });
 });