HBASE-25096 WAL size in RegionServer UI is wrong

Signed-off-by: Guanghao Zhang <zghao@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperImpl.java

@@ -769,7 +769,7 @@ class MetricsRegionServerWrapperImpl
                 + (metaProvider == null ? 0 : metaProvider.getNumLogFiles());
         walFileSize =
             (provider == null ? 0 : provider.getLogFileSize())
-                + (provider == null ? 0 : provider.getLogFileSize());
+                + (metaProvider == null ? 0 : metaProvider.getLogFileSize());
         // Copy over computed values so that no thread sees half computed values.
         numStores = tempNumStores;
         numStoreFiles = tempNumStoreFiles;