解决timescaledb插件,时序表查看指定的SQL执行计划不准确

（cherry picked commit from <gitee.com//opengauss/openGauss-server/commit/a7b6f5cad7f11e7d2c0a4419f8b06970018f993a>

src/common/backend/utils/adt/ruleutils.cpp

@@ -8893,13 +8893,14 @@ static char* get_variable(
 
     /* Identify names to use */
     schemaname = NULL; /* default assumptions */
-    refname = rte->eref->aliasname;
 
     if (NULL != rte->relname && u_sess->hook_cxt.forTsdbHook) {
         rte->relname = get_rel_name(rte->relid);
         rte->eref->aliasname = rte->relname;
     }
 
+    refname = rte->eref->aliasname;
+
     /* Exceptions occur only if the RTE is alias-less */
     if (rte->alias == NULL) {
         if (rte->rtekind == RTE_RELATION || no_alias) {