Unskips serverless user profile API tests (elastic#165516)

Closes elastic#165769 
Closes elastic#165391

Unskips the serverless user profile API integration tests (still skipped
for MKI only).

Flaky Runner:
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3166

x-pack/test_serverless/api_integration/test_suites/common/security/user_profiles.ts

@@ -16,8 +16,7 @@ export default function ({ getService }: FtrProviderContext) {
 
   describe('security/user_profiles', function () {
     describe('route access', () => {
-      // FLAKY: https://github.com/elastic/kibana/issues/165391
-      describe.skip('internal', () => {
+      describe('internal', () => {
         // When we run tests on MKI, SAML realm is configured differently, and we cannot handcraft SAML responses to
         // log in as SAML users.
         this.tags(['skipMKI']);