chore: Add gcp resource name span attribute

Author: surbhigarg92

google-cloud-spanner/src/main/java/com/google/cloud/spanner/TraceWrapper.java

@@ -57,6 +57,7 @@ class TraceWrapper {
       AttributeKey.stringKey("gcp.client.repo");
   private static final AttributeKey<String> GCP_RESOURCE_NAME_KEY =
       AttributeKey.stringKey("gcp.resource.name");
+  private static final String GCP_RESOURCE_NAME_PREFIX = "//spanner.googleapis.com/";
   private static final AttributeKey<String> THREAD_NAME_KEY = AttributeKey.stringKey("thread.name");
 
   private final Tracer openCensusTracer;
@@ -221,7 +222,7 @@ Attributes createDatabaseAttributes(DatabaseId db) {
     AttributesBuilder builder = Attributes.builder();
     builder.put(DB_NAME_KEY, db.getDatabase());
     builder.put(INSTANCE_NAME_KEY, db.getInstanceId().getInstance());
-    builder.put(GCP_RESOURCE_NAME_KEY, "//spanner.googleapis.com/" + db.getName());
+    builder.put(GCP_RESOURCE_NAME_KEY, GCP_RESOURCE_NAME_PREFIX + db.getName());
     return builder.build();
   }