[CI] skip flaky integration test (elastic#204645)

## Summary
Skips suite "reindex & waitForReindexTask"
- Errors are reported here:
elastic#167273
- Original issue, I believe:
elastic#166190
- PR that recently unskipped the test:
elastic#204561

(cherry picked from commit e529a89)

src/core/server/integration_tests/saved_objects/migrations/group3/actions/actions_test_suite.ts

@@ -772,7 +772,9 @@ export const runActionTestSuite = ({
 
   // Reindex doesn't return any errors on its own, so we have to test
   // together with waitForReindexTask
-  describe('reindex & waitForReindexTask', () => {
+  // Flaky: https://github.com/elastic/kibana/issues/166190
+  // Reported here: https://github.com/elastic/kibana/issues/167273
+  describe.skip('reindex & waitForReindexTask', () => {
     it('resolves right when reindex succeeds without reindex script', async () => {
       const res = (await reindex({
         client,