[FIX] point_of_sale: pay button too small

A previous PR made the Pay button smaller than it should.
This old PR was created to correct a bug in the mobile view by removing
the "More" button if it was not needed and thus making the validation
button bigger when there was no "More" button. It led to a problem
where, in desktop view, the "More" button is not present but the page
act like it was present and thus make the validation button smaller than
it should have. This commit add the condition that the screen must be in
mobile mode to shrink the validation button size.

closes odoo/odoo#128677

Signed-off-by: David Monnom (moda) <moda@odoo.com>

addons/point_of_sale/static/src/app/screens/product_screen/action_pad/action_pad.xml

@@ -16,7 +16,7 @@
                     Customer
                 </t>
             </button>
-            <button class="button pay validation pay-order-button" t-att-class="{ 'with-more-button': props.onClickMore }" t-on-click="props.actionToTrigger ? this.props.actionToTrigger : () => pos.get_order().pay()">
+            <button class="button pay validation pay-order-button" t-att-class="{ 'with-more-button': props.onClickMore and ui.isSmall }" t-on-click="props.actionToTrigger ? this.props.actionToTrigger : () => pos.get_order().pay()">
                 <div class="pay-circle" t-att-class="{ 'highlight': this.highlightPay }">
                     <i class="oi oi-chevron-right" role="img" aria-label="Pay" title="Pay" />
                 </div>