chore(datepicker): remove unnecessary var definition

Author: didimmova

src/components/date-picker/themes/shared/date-picker.common.scss

@@ -7,7 +7,6 @@ $input-theme: input-theme.$material;
 
 :host {
     --component-size: var(--ig-size, #{var-get($theme, 'default-size')});
-    --input-size: var(--component-size);
 
     igc-dialog {
         box-shadow: none;