fix: mark readRow requests as unary operations (#1679)

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Fixes #<issue_number_goes_here> ☕️

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Author: mutianf

README.md

@@ -49,7 +49,7 @@ If you are using Maven without BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.10.0')
+implementation platform('com.google.cloud:libraries-bom:26.11.0')
 
 implementation 'com.google.cloud:google-cloud-bigtable'
 ```

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/stub/EnhancedBigtableStub.java

@@ -395,13 +395,13 @@ public <RowT> UnaryCallable<Query, RowT> createReadRowCallable(RowAdapter<RowT>
     ReadRowsUserCallable<RowT> readRowCallable =
         new ReadRowsUserCallable<>(readRowsCallable, requestContext);
 
-    ServerStreamingCallable<Query, RowT> traced =
-        new TracedServerStreamingCallable<>(
-            readRowCallable, clientContext.getTracerFactory(), getSpanName("ReadRow"));
+    ReadRowsFirstCallable<RowT> firstRow = new ReadRowsFirstCallable<>(readRowCallable);
 
-    ReadRowsFirstCallable<RowT> firstRow = new ReadRowsFirstCallable<>(traced);
+    UnaryCallable<Query, RowT> traced =
+        new TracedUnaryCallable<>(
+            firstRow, clientContext.getTracerFactory(), getSpanName("ReadRow"));
 
-    return firstRow.withDefaultCallContext(clientContext.getDefaultCallContext());
+    return traced.withDefaultCallContext(clientContext.getDefaultCallContext());
   }
 
   /**