[server] print snapshot size in snapshot finish log (#2516)

Author: zuston

fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/PeriodicSnapshotManager.java

@@ -244,9 +244,11 @@ private void asyncSnapshotPhase(
                                             snapshotLocation,
                                             snapshotResult);
                                     LOG.info(
-                                            "TableBucket {} snapshot {} finished successfully, cost {} ms.",
+                                            "TableBucket {} snapshot {} finished successfully, full size: {}, incremental size: {}, cost: {} ms.",
                                             tableBucket,
                                             snapshotId,
+                                            snapshotResult.getSnapshotSize(),
+                                            snapshotResult.getIncrementalSize(),
                                             System.currentTimeMillis() - triggerTime);
                                 } catch (Throwable t) {
                                     LOG.warn(

fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/SnapshotResult.java

@@ -56,4 +56,8 @@ public long getLogOffset() {
     public long getSnapshotSize() {
         return kvSnapshotHandle.getSnapshotSize();
     }
+
+    public long getIncrementalSize() {
+        return kvSnapshotHandle.getIncrementalSize();
+    }
 }