RUM-9899: fix configuration

Author: satween

detekt_custom.yml

@@ -751,6 +751,7 @@ datadog:
       - "java.util.concurrent.atomic.AtomicLong.set(kotlin.Long)"
       - "java.util.concurrent.atomic.AtomicReference.compareAndSet(com.datadog.trace.core.CoreTracer?, com.datadog.trace.core.CoreTracer?)"
       - "java.util.concurrent.atomic.AtomicReference.compareAndSet(com.datadog.android.api.SdkCore?, com.datadog.android.api.SdkCore?)"
+      - "java.util.concurrent.atomic.AtomicReference.compareAndSet(com.datadog.trace.bootstrap.instrumentation.api.AgentTracer.TracerAPI?, com.datadog.trace.bootstrap.instrumentation.api.AgentTracer.TracerAPI?)"
       - "java.util.concurrent.atomic.AtomicReference.compareAndSet(io.opentracing.Tracer?, io.opentracing.Tracer?)"
       - "java.util.concurrent.atomic.AtomicReference.constructor()"
       - "java.util.concurrent.atomic.AtomicReference.constructor(android.app.Application.ActivityLifecycleCallbacks?)"
@@ -764,6 +765,7 @@ datadog:
       - "java.util.concurrent.atomic.AtomicReference.set(com.datadog.android.api.SdkCore?)"
       - "java.util.concurrent.atomic.AtomicReference.set(com.datadog.android.api.feature.FeatureEventReceiver?)"
       - "java.util.concurrent.atomic.AtomicReference.set(com.datadog.android.rum.internal.domain.RumContext?)"
+      - "java.util.concurrent.atomic.AtomicReference.set(com.datadog.trace.bootstrap.instrumentation.api.AgentTracer.TracerAPI?)"
       - "java.util.concurrent.atomic.AtomicReference.set(com.datadog.trace.core.CoreTracer?)"
       - "java.util.concurrent.atomic.AtomicReference.set(io.opentracing.Tracer?)"
       - "java.util.concurrent.atomic.AtomicReference.set(kotlin.Nothing?)"

features/dd-sdk-android-trace-internal/src/main/java/com/datadog/trace/core/PendingTrace.java

@@ -225,6 +225,7 @@ void registerSpan(final DDSpan span) {
 
     public void unregisterSpan(final DDSpan span){
         PENDING_REFERENCE_COUNT.decrementAndGet(this);
+        ROOT_SPAN.compareAndSet(this, span, null);
         if (pendingTraceBuffer.longRunningSpansEnabled()){
             spans.remove(span);
         }