feat: remove unnecessary synchronization

See: [#14047](#14047)

Author: jhayes2-chwy

instrumentation/runtime-telemetry/runtime-telemetry-java17/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/java17/internal/AbstractThreadDispatchingHandler.java

@@ -5,7 +5,6 @@
 
 package io.opentelemetry.instrumentation.runtimemetrics.java17.internal;
 
-import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.function.Consumer;
@@ -16,17 +15,15 @@
  * any time.
  */
 public abstract class AbstractThreadDispatchingHandler implements RecordedEventHandler {
+  // Use an access-ordered LinkedHashMap so we get a bounded LRU cache
   private final Map<String, Consumer<RecordedEvent>> perThread =
-      Collections.synchronizedMap(
-          // Use an access-ordered LinkedHashMap so we get a bounded LRU cache
-          new LinkedHashMap<String, Consumer<RecordedEvent>>(16, 0.75F, true) {
-
-            @Override
-            protected boolean removeEldestEntry(Map.Entry<String, Consumer<RecordedEvent>> eldest) {
-              // Bound this map to prevent memory leaks with fast-cycling thread frameworks
-              return size() > 1024;
-            }
-          });
+      new LinkedHashMap<String, Consumer<RecordedEvent>>(16, 0.75F, true) {
+        @Override
+        protected boolean removeEldestEntry(Map.Entry<String, Consumer<RecordedEvent>> eldest) {
+          // Bound this map to prevent memory leaks with fast-cycling thread frameworks
+          return size() > 512;
+        }
+      };
   private final ThreadGrouper grouper;
 
   protected AbstractThreadDispatchingHandler(ThreadGrouper grouper) {