Remove redundant assignment of default values to volatile/atomic fields

Closes gh-27477

spring-core/src/main/java/org/springframework/core/metrics/jfr/FlightRecorderApplicationStartup.java

@@ -38,7 +38,7 @@ import org.springframework.core.metrics.StartupStep;
  */
 public class FlightRecorderApplicationStartup implements ApplicationStartup {
 
-	private final AtomicLong currentSequenceId = new AtomicLong(0);
+	private final AtomicLong currentSequenceId = new AtomicLong();
 
 	private final Deque<Long> currentSteps;