Spring Boot starter fails to start when converters have been added manually

Describe the bug

Based on https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/10268#issuecomment-2940265751

Steps to reproduce

@SpringBootConfiguration
@EnableAutoConfiguration(
        exclude = {
                HibernateJpaAutoConfiguration.class,
                ActiveMQAutoConfiguration.class,
                JmsAutoConfiguration.class,
                NettyAutoConfiguration.class,
                JmxAutoConfiguration.class,
                JmxEndpointAutoConfiguration.class,
                DataSourceAutoConfiguration.class
        }
)
public class SoSmall {
    @Configuration
    static class MyConf {
        @Bean
        public ConversionService conversionService() {
            return new DefaultFormattingConversionService();
        }
    }

    public static void main(final String[] args) {
        final ConfigurableApplicationContext context = new SpringApplicationBuilder(SoSmall.class).web(WebApplicationType.NONE)
                .run(args);
        final SoSmall smol = context.getBean(SoSmall.class);

        smol.run(context);

        context.close();
    }

    private void run(ConfigurableApplicationContext context) {
        System.out.println("Hello!");
    }
}

Expected behavior

Should start

Actual behavior

APPLICATION FAILED TO START

Description:

Failed to bind properties under 'otel.resource.attributes' to java.util.Map<java.lang.String, java.lang.String>:

Property: otel.resource.attributes
Value: "a=b,c=d"
Origin: class path resource [application.yaml] - 4:27
Reason: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.util.Map<java.lang.String, java.lang.String>]

Javaagent or library instrumentation version

5c208e643074da44bfa527c449c712d9040dac2a (https://github.com/open-telemetry/opentelemetry-java-instrumentation/pull/13972)

Environment

No response

Additional context

No response