[FIX] web: fix oe_stat_button dropdown width and button alignment

In the stat buttons' dropdown under "More", if the text is too long
a horizontal scroll appears.

Fixed by removing the fixed `width` and the `w-100` class on the
dropdown box.

Because of `height: 100%` which is needed for the button to be aligned
with the other buttons, the contents of the dropdown button are not
centered.

Fixed with a `d-flex` and `align-items-center`.

task-3573807

Part-of: odoo/odoo#141163

addons/web/static/src/views/form/button_box/button_box.scss

@@ -138,7 +138,6 @@
         }
 
         .o_dropdown_more {
-            width: 150px;
 
             .oe_stat_button {
                 height: auto;

addons/web/static/src/views/form/button_box/button_box.xml

@@ -8,7 +8,7 @@
     <div class="o-form-buttonbox position-relative d-flex w-md-auto" t-attf-class="{{ visibleButtons.length >= getMaxButtons() ? 'o_full w-100' : 'o_not_full'}} {{this.props.class}}">
         <t t-slot="{{ button_value }}" t-foreach="visibleButtons" t-as="button" t-key="button_value"/>
         <t t-if="additionalButtons.length" >
-            <Dropdown position="'bottom-end'" togglerClass="'o_button_more btn btn-outline-secondary'" menuClass="'o_dropdown_more position-absolute top-100 w-100 p-0 border-0'" class="'oe_stat_button btn position-relative p-0 border-0'">
+            <Dropdown position="'bottom-end'" togglerClass="'o_button_more btn btn-outline-secondary d-flex justify-content-center align-items-center'" menuClass="'o_dropdown_more position-absolute top-100 p-0 border-0'" class="'oe_stat_button btn position-relative p-0 border-0'">
                 <t t-set-slot="toggler"><span>More</span></t>
                 <DropdownItem t-foreach="additionalButtons" t-as="button" t-key="button_value" class="'d-flex flex-column p-0'">
                     <t t-slot="{{ button_value }}" />