_field_caps doesn't honour ignore_unavailable option with closed index

[bpintea]

Elasticsearch Version

8.14, also current master (@8201172)

Installed Plugins

No response

Java Version

bundled

OS Version

macos

Problem Description

Querying an inexistent index'es _field_caps with ignore_unavailable=true will work (returns no caps).
The same, but with an existing and closed index fails with cluster_block_exception.

Steps to Reproduce

1. PUT myindex
2. POST myindex/_close
3. GET myindex/_field_caps?fields=*&ignore_unavailable=true

Logs (if relevant)

Last step will fail with:

{
    "error": {
        "root_cause": [
            {
                "type": "cluster_block_exception",
                "reason": "index [myindex] blocked by: [FORBIDDEN/4/index closed];"
            }
        ],
        "type": "cluster_block_exception",
        "reason": "index [myindex] blocked by: [FORBIDDEN/4/index closed];"
    },
    "status": 403
}

[elasticsearchmachine]

Pinging @elastic/es-search (Team:Search)

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)