Kibana version: 7.10.1
Elasticsearch version: 7.10.1

Describe the bug:

The user role management screen does not allow you to add specific index privileges, even if they exist within Elasticsearch, such as indices:data/write/reindex.

This is the same as elastic/kibana#42975, except for index permissions instead of cluster ones.

**Steps to reprodu

In kibana I am updating the advanced settings page to sync the search text to the query URL search params (elastic/kibana#81829). This allows the URL to possibly be formatted incorrectly. Thus, running Query.parse('category:(accessibility))') will throw an error.

I am testing Query.parse before passing to EuiSearchBar and displaying a warning toast in case of an

The chaos job introduced in #3706 could be improved to make the process less "predictable":

• Chaos job could immediately scale-up the number of operator replicas
• As described in elastic/cloud-on-k8s#3706 (comment) we could use something like https://github.com/lthibault/jitterbug to make the delay between operations random.