[Security Solution] Make prebuilt rules bootstrap errors visible (elastic#239521)

**Partially addresses:** elastic#188090

## Summary

Prebuilt Rules bootstrap API endpoint may fail on a fresh deployment in Elastic Cloud. This PR rearranges assertions to provide an ability to view the error message.

Author: maximpn

x-pack/solutions/security/test/security_solution_api_integration/test_suites/detections_response/rules_management/prebuilt_rules/oom_testing/install_prebuilt_rules/install_prebuilt_rules.ts

@@ -59,10 +59,10 @@ export default ({ getService }: FtrProviderContext): void => {
     });
 
     it('install prebuilt rules from a package', async () => {
-      const { body: bootstrapPrebuiltRulesResponse } = await detectionsApi
-        .bootstrapPrebuiltRules()
-        .expect(200);
+      const { statusCode: bootstrapPrebuiltRulesStatusCode, body: bootstrapPrebuiltRulesResponse } =
+        await detectionsApi.bootstrapPrebuiltRules();
 
+      // Assert body first to be able to see error messages in case of failure
       expect(bootstrapPrebuiltRulesResponse).toMatchObject({
         packages: expect.arrayContaining([
           expect.objectContaining({
@@ -73,6 +73,7 @@ export default ({ getService }: FtrProviderContext): void => {
           }),
         ]),
       });
+      expect(bootstrapPrebuiltRulesStatusCode).toBe(200);
 
       const { body: reviewPrebuiltRulesForInstallationResponse } = await supertest
         .post(REVIEW_RULE_INSTALLATION_URL)