[BUG] [Rust] Enum duplicates for negative and positive integers

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

openapi-generator version

5.4.0-SNAPSHOT (Git SHA 8a3b434d54de4639295a34c332707678d4f44038)

OpenAPI declaration file content or url

Using code from equivalent bug for PHP: https://github.com/OpenAPITools/openapi-generator/issues/7441

https://gist.github.com/victorlap/44e351b72f5d9f26f0ac1943b4c6cf22

Generation Details

java -jar openapi-generator/modules/openapi-generator-cli/target/openapi-generator-cli.jar generate --input-spec spec.json   --generator-name rust --output issue7441

Steps to reproduce

Run the above command on the spec that is linked in the gist.
Check file issue7441/src/models/sales_order_billingaddress.rs and see duplicate const declaration:

pub enum CustomForm {
    #[serde(rename = "-1049")]
    _1049,
    #[serde(rename = "1049")]
    _1049,
}

Related issues/PRs

PHP: https://github.com/OpenAPITools/openapi-generator/issues/7441

Suggest a fix

This may be a language-independent problem. Adding code at https://github.com/OpenAPITools/openapi-generator/blob/8a3b434d54de4639295a34c332707678d4f44038/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java#L5914 to check if toEnumVarName(enumName, dataType) is present in the name field of an existing entry in enumVars and adding a disambiguating suffix if so, may work.

Reproduce the issue with the linked gist and the provided openapi-generator command, then inspect DefaultCodegen.java around the referenced enum variable generation code. Compare the generated issue7441/src/models/sales_order_billingaddress.rs output with the expected distinct Rust enum variant names; completion means the negative and positive values no longer produce duplicate declarations.