branch-2.1: [fix](regression-test) Fix potential multi FE desc table result not refresh after schema change #44989 (#45009)

Cherry-picked from #44989

Co-authored-by: Siyang Tang <tangsiyang@selectdb.com>

regression-test/framework/src/main/groovy/org/apache/doris/regression/suite/Suite.groovy

@@ -657,6 +657,8 @@ class Suite implements GroovyInterceptable {
         runAction(new WaitForAction(context), actionSupplier)
         if (ObjectUtils.isNotEmpty(insertSql)){
             sql insertSql
+        } else {
+            sql "SYNC"
         }
         if (cleanOperator==true){
             if (ObjectUtils.isEmpty(tbName)) throw new RuntimeException("tbName cloud not be null")