[BUG] The ignore_missing parameter has no effect when using template snippet in rename ingest processor

[gaobinlong]

Describe the bug
When creating a rename ingest processor, set field to a template snippet {{field_a}} and set ignore_missing to true, if field_a doesn't exist in the document, the processor throws an error rather than doing nothing.

To Reproduce
Steps to reproduce the behavior:

POST _ingest/pipeline/_simulate
{
  "pipeline" :
  {
    "processors": [
      {
        "rename" : {
          "field" : "{{foo_1}}",
          "target_field": "zoo", 
          "ignore_missing": true
        }
      }
    ]
  },
  "docs": [
    {
      "_index": "index",
      "_id": "id",
      "_source": {
        "foo":"bar"
      }
    }
  ]
}

, then we get:

{
  "docs": [
    {
      "error": {
        "root_cause": [
          {
            "type": "illegal_argument_exception",
            "reason": "path cannot be null nor empty"
          }
        ],
        "type": "illegal_argument_exception",
        "reason": "path cannot be null nor empty"
      }
    }
  ]
}

The result of setting ignore_missing to true and false are the same.
Expected behavior
When setting ignore_missing to true, rename ingest processor exits quietly without throwing an error.

Host/Environment (please complete the following information):

• OS: [Mac OS]
• Version [OpenSearch 2.9]

[gaobinlong]

Fixed by #9725.