clean up unnecessary code

Author: mmalerba

src/material/checkbox/_checkbox-private.scss

@@ -1,16 +1,11 @@
-@use '@material/checkbox/checkbox' as mdc-checkbox;
-@use '@material/checkbox/checkbox-theme' as mdc-checkbox-theme;
-@use '@material/form-field' as mdc-form-field;
-@use '@material/theme/theme-color' as mdc-theme-color;
-@use '@material/theme/theme';
 @use 'sass:map';
 @use 'sass:color';
-@use '../core/ripple/ripple-theme';
+@use '@material/checkbox/checkbox-theme' as mdc-checkbox-theme;
+@use '@material/form-field' as mdc-form-field;
 @use '../core/theming/theming';
 @use '../core/typography/typography';
 @use '../core/mdc-helpers/mdc-helpers';
 @use '../core/tokens/m2/mdc/checkbox' as tokens-mdc-checkbox;
-@use './checkbox-private';
 
 @mixin color($config-or-theme) {
   $config: theming.get-color-config($config-or-theme);

src/material/checkbox/_checkbox-theme.import.scss

@@ -1,19 +1,16 @@
+@use 'sass:map';
 @use '@angular/cdk';
 @use '@material/checkbox/checkbox' as mdc-checkbox;
 @use '@material/checkbox/checkbox-theme' as mdc-checkbox-theme;
 @use '@material/form-field' as mdc-form-field;
-@use '@material/ripple' as mdc-ripple;
 @use '@material/touch-target' as mdc-touch-target;
 @use '@material/theme/custom-properties' as mdc-custom-properties;
-@use 'sass:map';
 @use '../core/mdc-helpers/mdc-helpers';
 @use '../core/style/layout-common';
 @use '../core/style/vendor-prefixes';
 @use '../core/tokens/m2/mdc/checkbox' as tokens-mdc-checkbox;
 @use '../core/tokens/token-utils';
 
-@use './checkbox-private';
-
 @include mdc-custom-properties.configure($emit-fallback-values: false, $emit-fallback-vars: false) {
   // Add the checkbox static styles.
   @include mdc-checkbox.static-styles();