[BUG] Dynamic templates with path_match array don't work because its value is wrongly resolved as string

[fs-chris]

Describe the bug

Dynamic mapping in component templates do not work when using a path_match array.
The path_match array property is wrongly resolved to a string containing the JSON array when being applied to a new index.
I.e.,

...        "path_match": [
              "a.*",
              "b.*"
            ], ...

becomes

...    "path_match": "[a.*, b.*]", ...

which never matches.

Related component

Other

To Reproduce

1. Create component template with dynamic mapping using a path_match array

PUT _component_template/test
{
  "template": {
    "mappings": {
      "dynamic_templates": [
        {
          "test": {
            "path_match": [
              "a.*",
              "b.*"
            ],
            "mapping": {
              "type": "keyword"
            }
          }
        }
      ]
    }
  }
}

2. Verify the correctly stored template

GET _component_template/test  
{ 
  "component_templates": [ 
    { 
      "name": "test",
      "component_template": { 
        "template": { 
          "mappings": { 
            "dynamic_templates": [ 
              { 
                "test": { 
                  "path_match": [ 
                    "a.*",
                    "b.*"
                  ],
                  "mapping": { 
                    "type": "keyword"
            ...

3. Create index template that applies the mapping to test indexes

PUT _index_template/test
{
  "index_patterns": [
    "test*"
  ],
  "composed_of": [
    "test"
  ]
}

4. Store a document into a test index

PUT test-1/_doc/1
{
  "a": {
    "x": "Hello"
  },
  "b": {
    "y": "world"
  }
}

5. Check the mapping of the newly created index
   -> the path_match property is wrongly stored as single string
   -> the intended dynamic mapping was not applied to the properties; instead the properties are defined with the default type text (and keyword sub-field).

GET test-1/_mapping
{ 
  "test-1": { 
    "mappings": { 
      "dynamic_templates": [ 
        { 
          "test": { 
            "path_match": "[a.*, b.*]",
            "mapping": { 
              "type": "keyword"
            }
          }
        }
      ],
      "properties": { 
        "a": { 
          "properties": { 
            "x": { 
              "type": "text",
              "fields": { 
                "keyword": { 
                  "type": "keyword",
                  "ignore_above": 256
                }
              }
            }
          }
        },
        "b": { 
          "properties": { 
            "y": { 
              "type": "text",
              "fields": { 
                "keyword": { 
                  "type": "keyword",
                  "ignore_above": 256
                }
       ...

Expected behavior

The JSON array containing separate match patterns should be preserved when applying the template to a new index.

Additional Details

Plugins
none

Screenshots
n/a

Host/Environment (please complete the following information):

• OpenSearch 2.17.1 (Docker image)

Additional context
n/a