### Elasticsearch Version

8.3.2

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

Ubuntu 20.04.4 LTS

### Problem Description

When we have two legacy index templates and one of them defines the field name with dots (.), we may get mapper_parsing_exception.

### Steps to Reproduce

1. create two legacy index templates
```
PUT /_template/template1
{
  "order": 100,
  "index_patterns": [
    "haha*"
  ],
  "settings": {},
  "mappings": {
    "properties": {
      "kwm": {
        "properties": {
          "source": {
            "properties": {
              "geo": {
                "properties": {
                  "location": {
                    "type": "geo_point"
                  }
                }
              }
            }
          }
        }
      },
      "source": {
        "properties": {
          "geo": {
            "properties": {
              "location": {
                "type": "geo_point"
              }
            }
          }
        }
      }
    }
  }
}

PUT /_template/template2
{
  "order": 10,
  "index_patterns": [
    "haha*"
  ],
  "settings": {},
  "mappings": {
    "properties": {
      "kwm.source.geo": {
        "properties": {
          "location": {
            "type": "geo_point"
          }
        }
      }
    }
  }
}
```
3. try to create an index
```
POST haha/_doc
{
}
```
it produces `mapper_parsing_exception` in `8.3.2` as below
```
{
  "error": {
    "root_cause": [
      {
        "type": "mapper_parsing_exception",
        "reason": "Field [source.geo.location] is defined more than once"
      }
    ],
    "type": "mapper_parsing_exception",
    "reason": "Field [source.geo.location] is defined more than once"
  },
  "status": 400
}
```
but no error in `8.2.3`

4. if we change the second index template `template2` as below:
```
PUT /_template/template2
{
  "order": 10,
  "index_patterns": [
    "haha*"
  ],
  "settings": {},
  "mappings": {
    "properties": {
      "kwm": {
        "properties": {
          "source": {
            "properties": {
              "geo": {
                "properties": {
                  "location": {
                    "type": "geo_point"
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}
```
we can create the `haha` index without errors in both `8.3.2` and `8.2.3`

I think we should not get `mapper_parsing_exception` in both `8.3.2` and `8.2.3` in the step 3 because `kwm.source.geo.location` field definition of two index templates are identical and `source.geo.location` is defined only in the `template1` index template.
I think this may be related with https://github.com/elastic/elasticsearch/pull/86166

### Logs (if relevant)

_No response_
server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java
}
                    }
                    if (objBuilder.subobjects.value() == false && type.equals(ObjectMapper.CONTENT_TYPE)) {
                        throw new MapperParsingException(
                            "Tried to add subobject ["
                                + fieldName
                                + "] to object ["
                                + objBuilder.name()
                                + "] which does not support subobjects"
                        );
                    }
                    if (objBuilder.subobjects.value() == false && type.equals(NestedObjectMapper.CONTENT_TYPE)) {
                        throw new MapperParsingException(
                            "Tried to add nested object ["
                                + fieldName
                                + "] to object ["
                                + objBuilder.name()
                                + "] which does not support subobjects"
                        );
                    }
                    Mapper.TypeParser typeParser = parserContext.typeParser(type);
                    if (typeParser == null) {
                        throw new MapperParsingException("No handler for type [" + type + "] declared on field [" + fieldName + "]");
                    }
                    Mapper.Builder fieldBuilder;
                    if (objBuilder.subobjects.value() == false) {
                        fieldBuilder = typeParser.parse(fieldName, propNode, parserContext);
                    } else {
                        String[] fieldNameParts = fieldName.split("\\.");
                        String realFieldName = fieldNameParts[fieldNameParts.length - 1];