[Cloud Security] fix vulnerability dashboard ftr flaky test (#187790)

## Summary

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gif.
Fix Flaky Vulnerability Dashboard Test

(cherry picked from commit 4b8ba30)

x-pack/test/cloud_security_posture_api/routes/vulnerabilities_dashboard.ts

@@ -186,16 +186,13 @@ export default function ({ getService }: FtrProviderContext) {
 
   describe('Vulnerability Dashboard API', async () => {
     beforeEach(async () => {
+      await index.removeFindings();
+      await index.removeScores();
       await waitForPluginInitialized();
       await index.addScores(scoresVulnerabilitiesMock);
       await index.addFindings(vulnerabilitiesLatestMock);
     });
 
-    afterEach(async () => {
-      await index.removeFindings();
-      await index.removeScores();
-    });
-
     it('responds with a 200 status code and matching data mock', async () => {
       const { body } = await supertest
         .get(`/internal/cloud_security_posture/vulnerabilities_dashboard`)