[BUG][Kotlin] Using <interfaceOnly>true</interfaceOnly> with kotlin-spring generator still generates controller body

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?
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Description

Using this spec as input: https://raw.githubusercontent.com/OAI/OpenAPI-Specification/main/examples/v3.0/petstore.yaml
and this configuration:

<configOptions>
    <interfaceOnly>true</interfaceOnly>
    <serviceInterface>true</serviceInterface>
...
</configOptions>

the generated methods still contain body and the code doesn't compile:

@RequestMapping("\${api.base-path:/v1}")
interface PetsApi {

    @Operation(
        summary = "Create a pet",
        operationId = "createPets",
        description = "",
        responses = [
            ApiResponse(responseCode = "201", description = "Null response"),
            ApiResponse(responseCode = "200", description = "unexpected error", content = [Content(schema = Schema(implementation = Error::class))])
        ]
    )
    @RequestMapping(
            method = [RequestMethod.POST],
            value = ["/pets"],
            produces = ["application/json"]
    )
    fun createPets(): ResponseEntity<Unit> {
        return ResponseEntity(service.createPets(), HttpStatus.valueOf(201)) // <=================
    }
...

Not only is method code generated but also it references a service (which is injected when interfaceOnly is false) which fails compilation with 'Unresolved reference: service'.

openapi-generator version

I'm using the org.openapitools:openapi-generator-maven-plugin:6.0.0 maven plugin (maven is 3.8.6).

OpenAPI declaration file content or url

https://raw.githubusercontent.com/OAI/OpenAPI-Specification/main/examples/v3.0/petstore.yaml

Start with the kotlin-spring generator using the linked petstore.yaml spec and the interfaceOnly=true and serviceInterface=true configuration. Compare the generated PetsApi methods with the reported output; done means interface-only methods no longer contain a body or reference the injected service, and the generated Kotlin code compiles.