Use consistently *KotlinTests naming for Kotlin tests

Closes gh-30837

spring-messaging/src/test/kotlin/org/springframework/messaging/converter/KotlinSerializationJsonMessageConverterTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,6 @@ import org.springframework.messaging.support.MessageBuilder
 import java.nio.charset.StandardCharsets
 import kotlin.reflect.typeOf
 
-@Suppress("UsePropertyAccessSyntax")
 class KotlinSerializationJsonMessageConverterTests {
 
 	private val converter = KotlinSerializationJsonMessageConverter()