(Fixes #22414) Rename for consistency `$custom-checkbox-radius`, `$custom-checkbox...

(Fixes #22414) Rename for consistency `$custom-checkbox-radius`, `$custom-checkbox-checked-icon`, `$custom-checkbox-indeterminate-indicator-color`, `$custom-checkbox-indeterminate-icon`, `$custom-radio-radius`, `$custom-radio-checked-icon`, `$custom-select-sm-font-size`, to `$custom-checkbox-border-radius`, `$custom-checkbox-icon-checked`, `$custom-checkbox-indicator-indeterminate-color`, `$custom-checkbox-icon-indeterminate`, `$custom-radio-border-radius`, `$custom-radio-icon-checked`, `$custom-select-font-size-sm` respectively