refactor(storage): implement Option C scoped metrics context and wire operations across transports

- Overload Retrier.run() and RetrierWithAlg.run() to accept @nullable StorageMetricsContext as the last parameter
- Constructor-inject @nullable StorageMetricsContext in DefaultRetrierWithAlg
- Attach StorageMetricsContext to GrpcCallContext in Retrying.newCallContext(metricsContext)
- Fast-path zero overhead in DefaultRetrier.run() when metrics are null/disabled
- Wrap execution in otelContext.makeCurrent() scope for trace exemplar collection
- Record raw exceptions before StorageException.coalesce()
- Wire operation-scoped metrics context across StorageImpl and GrpcStorageImpl
- Propagate StorageMetricsContext in GrpcStorageImpl pagination decorators
- Add rpc.system.name and server.address attributes to StorageClientMetrics
- Add comprehensive unit tests in RetryingMetricsTest, StorageClientMetricsTest, and StorageOptionsTest

[Generated-by: AI]

Author: nidhiii-27

java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/GrpcStorageImpl.java

@@ -127,28 +127,80 @@ final class StorageClientMetrics {
   static StorageClientMetrics create(
       MeterProvider meterProvider, boolean enableOtelMetrics, boolean enableOtelDebugMetrics) {
     return create(
-        meterProvider, UUID.randomUUID().toString(), enableOtelMetrics, enableOtelDebugMetrics);
+        meterProvider, enableOtelMetrics, enableOtelDebugMetrics, (String) null, (String) null);
   }
 
   static StorageClientMetrics create(
       MeterProvider meterProvider,
       String instanceId,
       boolean enableOtelMetrics,
       boolean enableOtelDebugMetrics) {
+    return create(
+        meterProvider,
+        enableOtelMetrics,
+        enableOtelDebugMetrics,
+        StorageOptions.version(),
+        instanceId,
+        null,
+        null);
+  }
+
+  static StorageClientMetrics create(
+      MeterProvider meterProvider,
+      boolean enableOtelMetrics,
+      boolean enableOtelDebugMetrics,
+      @Nullable String rpcSystemName,
+      @Nullable String serverAddress) {
+    return create(
+        meterProvider,
+        enableOtelMetrics,
+        enableOtelDebugMetrics,
+        StorageOptions.version(),
+        rpcSystemName,
+        serverAddress);
+  }
+
+  static StorageClientMetrics create(
+      MeterProvider meterProvider,
+      boolean enableOtelMetrics,
+      boolean enableOtelDebugMetrics,
+      String sdkVersion,
+      @Nullable String rpcSystemName,
+      @Nullable String serverAddress) {
+    return create(
+        meterProvider,
+        enableOtelMetrics,
+        enableOtelDebugMetrics,
+        sdkVersion,
+        UUID.randomUUID().toString(),
+        rpcSystemName,
+        serverAddress);
+  }
+
+  static StorageClientMetrics create(
+      MeterProvider meterProvider,
+      boolean enableOtelMetrics,
+      boolean enableOtelDebugMetrics,
+      String sdkVersion,
+      String instanceId,
+      @Nullable String rpcSystemName,
+      @Nullable String serverAddress) {
     Meter meter =
-        meterProvider
-            .meterBuilder(METER_NAME)
-            .setInstrumentationVersion(StorageOptions.version())
-            .build();
-    Attributes clientAttributes =
+        meterProvider.meterBuilder(METER_NAME).setInstrumentationVersion(sdkVersion).build();
+    AttributesBuilder builder =
         Attributes.builder()
             .put(KEY_GCP_CLIENT_SERVICE, SERVICE_STORAGE)
-            .put(KEY_GCP_CLIENT_VERSION, StorageOptions.version())
+            .put(KEY_GCP_CLIENT_VERSION, sdkVersion)
             .put(KEY_GCP_CLIENT_ARTIFACT, ARTIFACT_STORAGE)
-            .put(KEY_GCP_CLIENT_INSTANCE_ID, instanceId)
-            .build();
+            .put(KEY_GCP_CLIENT_INSTANCE_ID, instanceId);
+    if (rpcSystemName != null && !rpcSystemName.isEmpty()) {
+      builder.put(KEY_RPC_SYSTEM_NAME, rpcSystemName);
+    }
+    if (serverAddress != null && !serverAddress.isEmpty()) {
+      builder.put(KEY_SERVER_ADDRESS, serverAddress);
+    }
     return new StorageClientMetrics(
-        meter, clientAttributes, enableOtelMetrics, enableOtelDebugMetrics);
+        meter, builder.build(), enableOtelMetrics, enableOtelDebugMetrics);
   }
 
   StorageClientMetrics(Meter meter, boolean enableOtelMetrics, boolean enableOtelDebugMetrics) {