[BUG] bump ML config index schema version

[ylwu-amzn]

What is the bug?
ML config index mapping updated, but schema version not bumped. This PR #1995 updated

[dhrubo-os]

Same for .plugins-ml-config index.

In 2.9 index mapping definition is:

{
  ".plugins-ml-config" : {
    "mappings" : {
      "_meta" : {
        "schema_version" : 2
      },
      "properties" : {
        "create_time" : {
          "type" : "date",
          "format" : "strict_date_time||epoch_millis"
        },
        "master_key" : {
          "type" : "keyword"
        }
      }
    }
  }
}

and in 2.13 it is:

{
  ".plugins-ml-config" : {
    "mappings" : {
      "dynamic" : "strict",
      "_meta" : {
        "schema_version" : 2
      },
      "properties" : {
        "configuration" : {
          "type" : "flat_object"
        },
        "create_time" : {
          "type" : "date",
          "format" : "strict_date_time||epoch_millis"
        },
        "last_update_time" : {
          "type" : "date",
          "format" : "strict_date_time||epoch_millis"
        },
        "master_key" : {
          "type" : "keyword"
        },
        "type" : {
          "type" : "keyword"
        }
      }
    }
  }
}

this PR updated

[ylwu-amzn]

Sorry my bad, it should be ML config index, not model group .

[dhrubo-os]

I found another PR: https://github.com/opensearch-project/ml-commons/pull/2276/files where version didn't get bumped.