[fix](filecache) fix observation bug in multi-BE cluster (#59259)

BE_ID column should be in partition column list otherwise results from
all BE won't be merged and thus provides flickering results.

Author: freemandealer

fe/fe-core/src/main/java/org/apache/doris/planner/BackendPartitionedSchemaScanNode.java

@@ -70,6 +70,7 @@ public class BackendPartitionedSchemaScanNode extends SchemaScanNode {
         BEACKEND_ID_COLUMN_SET.add("be_id");
 
         BACKEND_TABLE.add("file_cache_statistics");
+        BACKEND_TABLE.add("file_cache_info");
         BACKEND_TABLE.add("backend_kerberos_ticket_cache");
 
         BACKEND_TABLE.add("backend_tablets");