fix(textarea): disabled state cursor (#14954)

Author: SisIvanova

projects/igniteui-angular/src/lib/core/styles/components/input/_input-group-theme.scss

@@ -1256,6 +1256,7 @@
 
     %form-group-textarea--disabled {
         color: var-get($theme, 'disabled-text-color') !important;
+        cursor: default;
 
         &::placeholder {
             color: var-get($theme, 'disabled-placeholder-color');