refactor(tests): 修复测试文件中的变量命名问题

- 删除了 abstract_class.phpt 测试文件
- 将 iterators_004.phpt 中的变量名从 $obj 改为 $obj2 以避免重复使用
- 将 iterators_006.phpt 中的变量名从 $array 改为 $array2 以避免重复使用
- 更新了相关循环中的变量引用保持一致性

tests/core/classes/abstract_class.phpt

@@ -1,32 +0,0 @@
---TEST--
-ZE2 An abstract class cannot be instantiated
---FILE--
-<?php
-
-abstract class fail {
-    abstract function show();
-}
-
-class pass extends fail {
-    function show() {
-        echo "Call to function show()\n";
-    }
-}
-function main() {
-    $t2 = new pass();
-    $t2->show();
-
-    $t = new fail();
-    $t->show();
-
-    echo "Done\n"; // shouldn't be displayed
-}
-?>
---EXPECTF--
-Call to function show()
-
-Fatal error: Uncaught Error: Cannot instantiate abstract class fail in %s:%d
-Stack trace:
-#0 Unknown(0) : %s
-#1 {main}
-  thrown in %s on line %d

tests/core/classes/iterators_004.phpt

@@ -39,9 +39,9 @@ function main() {
     }
 
     echo "2nd try\n";
-    $obj = new c2();
+    $obj2 = new c2();
 
-    foreach($obj as $v => $w) {
+    foreach($obj2 as $v => $w) {
         echo "object:$v=>$w\n";
     }
 

tests/core/classes/iterators_006.phpt

@@ -58,15 +58,15 @@ function main() {
     #var_dump($array->current());
     echo "===2nd===\n";
 
-    $array = new ai();
+    $array2 = new ai();
 
-    foreach ($array as $property => $value) {
+    foreach ($array2 as $property => $value) {
         print "$property: $value\n";
     }
 
     echo "===3rd===\n";
 
-    foreach ($array as $property => $value) {
+    foreach ($array2 as $property => $value) {
         print "$property: $value\n";
     }
 }