[Fix](Nereids) fix test leading suite and add tpch shape checking base on leading (#25842)

- fix test leading suite caused by sessionvariable setting error
- add tpch shape checking base on leading

fe/fe-core/src/main/java/org/apache/doris/nereids/hint/LeadingHint.java

@@ -484,7 +484,7 @@ public class LeadingHint extends Hint {
             this.setErrorMessage("duplicated table");
             return totalBitmap;
         }
-        if (getTablelist().size() != tables.size()) {
+        if (tables != null && getTablelist().size() != tables.size()) {
             this.setStatus(HintStatus.SYNTAX_ERROR);
             this.setErrorMessage("tables should be same as join tables");
             return totalBitmap;

fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java

@@ -2676,7 +2676,7 @@ public class SessionVariable implements Serializable, Writable {
             return;
         }
         setIsSingleSetVar(true);
-        VariableMgr.setVar(this, new SetVar(SessionVariable.DISABLE_JOIN_REORDER, new StringLiteral("false")));
+        VariableMgr.setVar(this, new SetVar(SessionVariable.DISABLE_JOIN_REORDER, new StringLiteral("true")));
     }
 
     // return number of variables by given variable annotation