[Authz] Cleanup of access tags functionality and documentation (#220231)

## Summary

Mandatory security config has been added in
https://github.com/elastic/kibana/pull/215180. This PR cleans up access
tags functionality, documentation and migration eslint rule
`no_deprecated_authz_config` that is no longer needed.


### Checklist
- [x]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [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

docs/extend/development-security.md

@@ -268,8 +268,12 @@ Unlike the Canvas example, Dev Tools does not require access to any saved object
 server.route({
  path: '/api/console/proxy',
  method: 'POST',
+ security: {
+  authz: {
+    requiredPrivileges: ['console'],
+  },
+ },
  config: {
-   tags: ['access:console'],
    handler: async (req, h) => {
      // ...
    }