test(spring-boot-jakarta): [Queue Instrumentation 22] Cover spring-kafka class-absence gate

`SentryKafkaQueueConfiguration` in `SentryAutoConfiguration` gates the
Kafka BPPs on both `org.springframework.kafka.core.KafkaTemplate` and
`io.sentry.kafka.SentryKafkaProducerInterceptor` being present on the
classpath. Only the latter was covered by a test.

Add a `FilteredClassLoader(KafkaTemplate::class.java)` test that asserts
neither `SentryKafkaProducerBeanPostProcessor` nor
`SentryKafkaConsumerBeanPostProcessor` is registered when spring-kafka
is missing, even with `sentry.enable-queue-tracing=true`.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: adinauer

sentry-spring-boot-jakarta/src/test/kotlin/io/sentry/spring/boot/jakarta/SentryKafkaAutoConfigurationTest.kt

@@ -9,6 +9,7 @@ import org.assertj.core.api.Assertions.assertThat
 import org.springframework.boot.autoconfigure.AutoConfigurations
 import org.springframework.boot.test.context.FilteredClassLoader
 import org.springframework.boot.test.context.runner.ApplicationContextRunner
+import org.springframework.kafka.core.KafkaTemplate
 
 class SentryKafkaAutoConfigurationTest {
 
@@ -34,6 +35,8 @@ class SentryKafkaAutoConfigurationTest {
   private val noSentryKafkaClassLoader =
     FilteredClassLoader(SentryKafkaProducerInterceptor::class.java)
 
+  private val noSpringKafkaClassLoader = FilteredClassLoader(KafkaTemplate::class.java)
+
   @Test
   fun `registers Kafka BPPs when queue tracing is enabled`() {
     contextRunner
@@ -64,6 +67,17 @@ class SentryKafkaAutoConfigurationTest {
       }
   }
 
+  @Test
+  fun `does not register Kafka BPPs when spring-kafka is not present`() {
+    contextRunner
+      .withClassLoader(noSpringKafkaClassLoader)
+      .withPropertyValues("sentry.enable-queue-tracing=true")
+      .run { context ->
+        assertThat(context).doesNotHaveBean(SentryKafkaProducerBeanPostProcessor::class.java)
+        assertThat(context).doesNotHaveBean(SentryKafkaConsumerBeanPostProcessor::class.java)
+      }
+  }
+
   @Test
   fun `does not register Kafka BPPs when queue tracing is explicitly false`() {
     contextRunner