Attempt to fix the flaky StackedOperatorsTest on CI by not attaching the context if it is already attached.

Author: ygree

dd-java-agent/instrumentation/resilience4j/resilience4j-reactor-2.0/src/main/java/datadog/trace/instrumentation/resilience4j/CircuitBreakerOperatorInstrumentation.java

@@ -40,7 +40,7 @@ public static void after(
               result,
               CircuitBreakerDecorator.DECORATE,
               circuitBreaker,
-              InstrumentationContext.get(Publisher.class, AgentSpan.class)::put);
+              InstrumentationContext.get(Publisher.class, AgentSpan.class)::putIfAbsent);
     }
   }
 }

dd-java-agent/instrumentation/resilience4j/resilience4j-reactor-2.0/src/main/java/datadog/trace/instrumentation/resilience4j/RetryOperatorInstrumentation.java

@@ -39,7 +39,7 @@ public static void after(
               result,
               RetryDecorator.DECORATE,
               retry,
-              InstrumentationContext.get(Publisher.class, AgentSpan.class)::put);
+              InstrumentationContext.get(Publisher.class, AgentSpan.class)::putIfAbsent);
     }
   }
 }