refactor: logic for subList method when retrieving all data (#5235)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.12.x

#### What this PR does / why we need it:
重构 ListResult.subList 方法在获取所有数据时的处理逻辑，只要 size 为 0 就返回所有数据

#### Does this PR introduce a user-facing change?
```release-note
None
```

api/src/main/java/run/halo/app/extension/ListResult.java

@@ -129,6 +129,9 @@ public static <T> ListResult<T> emptyResult() {
      */
     public static <T> List<T> subList(List<T> list, int page, int size) {
         if (page < 1) {
+            page = 1;
+        }
+        if (size < 1) {
             return list;
         }
         List<T> listSort = new ArrayList<>();

application/src/test/java/run/halo/app/extension/ListResultTest.java

@@ -43,4 +43,26 @@ void totalPages() {
         listResult = new ListResult<>(1, 0, 100, List.of());
         assertEquals(1, listResult.getTotalPages());
     }
+
+    @Test
+    void subListWhenSizeIsZero() {
+        var list = List.of(1, 2, 3, 4, 5);
+        assertSubList(list);
+
+        list = List.of(1);
+        assertSubList(list);
+    }
+
+    private void assertSubList(List<Integer> list) {
+        var result = ListResult.subList(list, 0, 0);
+        assertEquals(list, result);
+
+        result = ListResult.subList(list, 0, 1);
+        assertEquals(list.subList(0, 1), result);
+
+        result = ListResult.subList(list, 1, 0);
+        assertEquals(list, result);
+
+        assertEquals(list.subList(0, 1), ListResult.subList(list, -1, 1));
+    }
 }