[Security Solution][Endpoint][Response Actions] Enable feature flag for execute by default (#155686)

From 8.8 `responseActionExecuteEnabled` is set to `true` by default

## Summary

Enables the `responseActionExecuteEnabled` feature flag by default for
`execute` response action.


### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

x-pack/test/api_integration/apis/security/privileges_basic.ts

@@ -124,6 +124,7 @@ export default function ({ getService }: FtrProviderContext) {
               'trusted_applications_all',
               'trusted_applications_read',
               'file_operations_all',
+              'execute_operations_all',
             ],
             uptime: ['all', 'read', 'minimal_all', 'minimal_read'],
             securitySolutionCases: ['all', 'read', 'minimal_all', 'minimal_read', 'cases_delete'],