fix(uui-textarea): Don't hide placeholder text on focus (#751)

* Don't hide placeholder text on focus

* Remove blank line

Author: bjarnef

packages/uui-textarea/lib/uui-textarea.element.ts

@@ -332,14 +332,6 @@ export class UUITextareaElement extends FormControlMixin(LitElement) {
           var(--uui-color-border-emphasis)
         );
       }
-
-      textarea::placeholder {
-        transition: opacity 120ms;
-      }
-      :host(:not([readonly])) textarea:focus::placeholder {
-        opacity: 0;
-      }
-
       textarea:focus {
         outline: calc(2px * var(--uui-show-focus-outline, 1)) solid
           var(--uui-color-focus);