docs(samples): [Queue Instrumentation 30] Document OTel Kafka suppression fixture

The OTel Jakarta sample Kafka configs intentionally set
`sentry.enable-queue-tracing=true` so the coexistence system test
(`KafkaOtelCoexistenceSystemTest`, added in PR #5324) can assert that
Sentry's Spring Kafka auto-config (`SentryKafkaQueueConfiguration`)
stays suppressed even when the customer explicitly opts in.

Add a comment to each `application-kafka.properties` explaining the
deliberate choice and link it to the test, so the property does not
read as a copy/paste trap for customers. Also extend the test KDoc to
call out the fixture.

#skip-changelog

Author: adinauer

sentry-samples/sentry-samples-spring-boot-jakarta-opentelemetry-noagent/src/main/resources/application-kafka.properties

@@ -1,4 +1,6 @@
 # Kafka — activate with: --spring.profiles.active=kafka
+
+# Deliberate fixture for KafkaOtelCoexistenceSystemTest: must stay suppressed in OTel mode.
 sentry.enable-queue-tracing=true
 
 spring.kafka.bootstrap-servers=localhost:9092

sentry-samples/sentry-samples-spring-boot-jakarta-opentelemetry-noagent/src/test/kotlin/io/sentry/systemtest/KafkaOtelCoexistenceSystemTest.kt

@@ -16,6 +16,9 @@ import org.junit.Before
  * `queue.process` spans/transactions are *not* emitted. Any Kafka telemetry in OTel mode must come
  * from the OTel Kafka instrumentation, not from the Sentry Kafka integration.
  *
+ * The sample sets `sentry.enable-queue-tracing=true` on purpose: suppression must win even when the
+ * customer explicitly opts in.
+ *
  * Requires:
  * - The sample app running with `--spring.profiles.active=kafka`
  * - A Kafka broker at localhost:9092

sentry-samples/sentry-samples-spring-boot-jakarta-opentelemetry/src/main/resources/application-kafka.properties

@@ -1,4 +1,6 @@
 # Kafka — activate with: --spring.profiles.active=kafka
+
+# Deliberate fixture for KafkaOtelCoexistenceSystemTest: must stay suppressed in OTel mode.
 sentry.enable-queue-tracing=true
 
 spring.kafka.bootstrap-servers=localhost:9092

sentry-samples/sentry-samples-spring-boot-jakarta-opentelemetry/src/test/kotlin/io/sentry/systemtest/KafkaOtelCoexistenceSystemTest.kt

@@ -16,6 +16,9 @@ import org.junit.Before
  * `queue.process` spans/transactions are *not* emitted. Any Kafka telemetry in OTel mode must come
  * from the OTel Kafka instrumentation, not from the Sentry Kafka integration.
  *
+ * The sample sets `sentry.enable-queue-tracing=true` on purpose: suppression must win even when the
+ * customer explicitly opts in.
+ *
  * Requires:
  * - The sample app running with `--spring.profiles.active=kafka`
  * - A Kafka broker at localhost:9092