[Security Solution][Detections] Unskip tests for bulk editing index p…

…atterns (#138435)

**Ticket:** #138409
**Caused by:** #138304 (comment)

## Summary

The merge of #138304 caused unit tests for bulk editing index patterns to start failing. This PR was reverted by 0bc8cf7. The tests were skipped in 26a4783.

These tests are fully functional in `main`. Unskipping them.

x-pack/plugins/security_solution/server/lib/detection_engine/rules/bulk_actions/rule_params_modifier.test.ts

@@ -50,8 +50,7 @@ describe('ruleParamsModifier', () => {
     expect(editedRuleParams).toHaveProperty('version', ruleParamsMock.version + 1);
   });
 
-  // FLAKY: https://github.com/elastic/kibana/issues/138409
-  describe.skip('index_patterns', () => {
+  describe('index_patterns', () => {
     test('should add new index pattern to rule', () => {
       const editedRuleParams = ruleParamsModifier(ruleParamsMock, [
         {