refactor: Add actual index to 403 logs

[rodrigo-sp17]

Implements actual index debug logging. The functionality is achieved by parsing the request description and making a separate debug message to avoid leaking unnecessary details to the client.

Fixes #29714

[elasticmachine]

Pinging @elastic/es-security (Team:Security)

[tvernum]

Hi @rodrigo-sp17

This problem was resolved last year in #60357, and since ES 7.12.0 authorization service errors should include the index name when it is relevant.
For example

{
  "error": {
    "root_cause": [
      {
        "type": "security_exception",
        "reason": "action [indices:data/read/search] is unauthorized for user [test] on indices [foo], this action is granted by the index privileges [read,all]"
      }
    ],
    "type": "security_exception",
    "reason": "action [indices:data/read/search] is unauthorized for user [test] on indices [foo], this action is granted by the index privileges [read,all]"
  },
  "status": 403
}

However, if the user does not have access to perform the action on any index, and the request contains wildcards, then the action may fail before we resolve indices. In that case, the message will not list indices (because in fact the error is not index specific - the user cannot perform that action regardless of the index specified).