Disable Jackson XML support in RSocket codecs

Prior to this commit, having the `spring-boot-starter-rsocket` and the
`jackson-dataformat-xml` dependencies on classpath would result in a
`ClassCastException` when the RSocket auto-configuration tries to
configure Jackson CBOR codecs for RSocket strategies.

This commit disables the Jackson XML support for the CBOR codec in
RSocket.

Fixes gh-17425

Author: bclozel

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/rsocket/RSocketStrategiesAutoConfiguration.java

@@ -78,7 +78,7 @@ protected static class JacksonCborStrategyConfiguration {
 		@ConditionalOnBean(Jackson2ObjectMapperBuilder.class)
 		public RSocketStrategiesCustomizer jacksonCborRSocketStrategyCustomizer(Jackson2ObjectMapperBuilder builder) {
 			return (strategy) -> {
-				ObjectMapper objectMapper = builder.factory(new CBORFactory()).build();
+				ObjectMapper objectMapper = builder.createXmlMapper(false).factory(new CBORFactory()).build();
 				strategy.decoder(new Jackson2CborDecoder(objectMapper, SUPPORTED_TYPES));
 				strategy.encoder(new Jackson2CborEncoder(objectMapper, SUPPORTED_TYPES));
 			};