Fix spanner io hang by closing connections (#37327)

Author: damccorm

sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/SpannerIO.java

@@ -2101,9 +2101,10 @@ private static Dialect getDialect(SpannerConfig spannerConfig, PipelineOptions p
     // Allow passing the credential from pipeline options to the getDialect() call.
     SpannerConfig spannerConfigWithCredential =
         buildSpannerConfigWithCredential(spannerConfig, pipelineOptions);
-    DatabaseClient databaseClient =
-        SpannerAccessor.getOrCreate(spannerConfigWithCredential).getDatabaseClient();
-    return databaseClient.getDialect();
+    try (SpannerAccessor sa = SpannerAccessor.getOrCreate(spannerConfigWithCredential)) {
+      DatabaseClient databaseClient = sa.getDatabaseClient();
+      return databaseClient.getDialect();
+    }
   }
 
   /**