fix(gax): avoid potential NPE when resolving attempt span name

Author: jinseopkim0

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTracingTracer.java

@@ -140,7 +140,7 @@ public Scope inScope() {
     this.apiTracerContext = apiTracerContext;
     this.operationSpanName = operationSpanName;
     this.attemptSpanName =
-        attemptSpanName.equals(operationSpanName) ? attemptSpanName + "/attempt" : attemptSpanName;
+        operationSpanName.equals(attemptSpanName) ? attemptSpanName + "/attempt" : attemptSpanName;
     this.attemptAttributes = new HashMap<>();
     this.parentContext = io.opentelemetry.context.Context.current();
     buildAttributes();