#22771 Remove hardcoded height for admin textarea

Author: Serhiy Zhovnir

app/design/adminhtml/Magento/backend/web/css/source/forms/_controls.less

@@ -202,7 +202,6 @@ option:empty {
 
 .admin__control-textarea {
     &:extend(.abs-form-control-pattern all);
-    height: 8.48rem;
     line-height: 1.18;
     padding-top: .8rem;
     resize: vertical;