[fix](jdbc scan) 1=1 does not translate to TRUE (#21688)

For most database systems, they recognize where 1=1 but not where true, so we should send the original 1=1 to the database

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

@@ -134,6 +134,9 @@ public class JdbcScanNode extends ExternalScanNode {
         for (Expr p : conjunctsList) {
             if (shouldPushDownConjunct(jdbcType, p)) {
                 String filter = conjunctExprToString(jdbcType, p);
+                if (filter.equals("TRUE")) {
+                    filter = "1 = 1";
+                }
                 filters.add(filter);
                 conjuncts.remove(p);
             }