fix: TextArea height bug (#33055)

* fix: TextArea height bug when has `showCount`

close #33049

* fix snapshot

* revert form demo

components/form/style/components.less

@@ -7,11 +7,6 @@
 // =                      Children Component                      =
 // ================================================================
 .@{form-item-prefix-cls} {
-  .@{ant-prefix}-mentions,
-  textarea.@{ant-prefix}-input {
-    height: auto;
-  }
-
   // input[type=file]
   .@{ant-prefix}-upload {
     background: transparent;

components/input/__tests__/__snapshots__/demo.test.js.snap

@@ -3332,6 +3332,7 @@ exports[`renders ./components/input/demo/textarea-show-count.md correctly 1`] =
 <div
   class="ant-input-textarea ant-input-textarea-show-count"
   data-count="0 / 100"
+  style="height:120px"
 >
   <textarea
     class="ant-input"

components/input/demo/textarea-show-count.md

@@ -22,5 +22,8 @@ const onChange = e => {
   console.log('Change:', e.target.value);
 };
 
-ReactDOM.render(<TextArea showCount maxLength={100} onChange={onChange} />, mountNode);
+ReactDOM.render(
+  <TextArea showCount maxLength={100} style={{ height: 120 }} onChange={onChange} />,
+  mountNode,
+);
 ```

components/input/style/index.less

@@ -47,8 +47,13 @@
     }
   }
 
-  &-textarea {
-    &-show-count::after {
+  &-textarea-show-count {
+    // https://github.com/ant-design/ant-design/issues/33049
+    > .@{input-prefix-cls} {
+      height: 100%;
+    }
+
+    &::after {
       float: right;
       color: @text-color-secondary;
       white-space: nowrap;