[Observability][RAC] Users need view_index_metadata index privilege to view fields on Alerts page

[simianhacker]

Kibana version:

8.x (all versions)

Elasticsearch version:

8.x (all versions)

Original install method (e.g. download page, yum, from source, etc.):

ALL

Describe the bug:

When using a restricted role, the user is unable to see the fields in the fields selector on the Alerts page

Steps to reproduce:

1. Create a new role named test_role to match
   
2. Create user with the test_role
3. Log in with your new user
4. Create an alert that is triggering
5. Visit the Alerts page for Observability
6. Click on the "Fields" selector icon under the search bar. The selector will will be empty.

Expected behavior:

You shouldn't need special permissions on the .alert* index pattern to select fields. The work around is to add view_index_metadata to the .alerts* pattern for the role.

Any additional context:

Here is the call that is populating the fields.

kibana/x-pack/plugins/observability/public/pages/alerts/containers/alerts_page/alerts_page.tsx

Lines 160 to 163 in e74afc4

	fields: await dataViews.getFieldsForWildcard({
	pattern: indexNames.join(','),
	allowNoIndex: true,
	}),

This needs to be changed to use a query that is called by asInternalUser which is only available on the server. We should probably create a search strategy to generate dynamic index patterns similar to the index_fields search strategy from the timelines plugin.

[kobelb]

Unfortunately, DataViews weren't created to work with internal indices like the .alerts-* indices, where end-users don't have privileges to read data directly from the ES indices. We'll need to figure out a different way to get the list of alert fields. @XavierM - have you all solved this problem already when creating the shared alerts table?

[simianhacker]

This should be solved once we upgrade to the RAC shared alerts table (#132816).

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)

[jcger]

Fixed after closing #137988