Make enabled fields volatile in SdkTracer, SdkMeter, and MetricStorage implementations

Co-authored-by: trask <218610+trask@users.noreply.github.com>

Author: Copilot

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/SdkMeter.java

@@ -89,7 +89,7 @@ final class SdkMeter implements Meter {
   private final InstrumentationScopeInfo instrumentationScopeInfo;
   private final Map<RegisteredReader, MetricStorageRegistry> readerStorageRegistries;
 
-  private boolean meterEnabled;
+  private volatile boolean meterEnabled;
 
   SdkMeter(
       MeterProviderSharedState meterProviderSharedState,

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/AsynchronousMetricStorage.java

@@ -87,7 +87,7 @@ public final class AsynchronousMetricStorage<T extends PointData, U extends Exem
   private long startEpochNanos;
   private long epochNanos;
 
-  private boolean enabled;
+  private volatile boolean enabled;
 
   private AsynchronousMetricStorage(
       RegisteredReader registeredReader,

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/DefaultSynchronousMetricStorage.java

@@ -74,7 +74,7 @@ public final class DefaultSynchronousMetricStorage<T extends PointData, U extend
   private final ConcurrentLinkedQueue<AggregatorHandle<T, U>> aggregatorHandlePool =
       new ConcurrentLinkedQueue<>();
 
-  private boolean enabled;
+  private volatile boolean enabled;
 
   DefaultSynchronousMetricStorage(
       RegisteredReader registeredReader,

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkTracer.java

@@ -30,9 +30,8 @@ class SdkTracer implements Tracer {
 
   private final TracerSharedState sharedState;
   private final InstrumentationScopeInfo instrumentationScopeInfo;
-  // deliberately not volatile because of performance concerns
-  // - which means its eventually consistent
-  protected boolean tracerEnabled;
+
+  protected volatile boolean tracerEnabled;
 
   SdkTracer(
       TracerSharedState sharedState,