[FIX] web: color of tooltip arrow

Prior to this commit, the color of the tooltip arrow didn't match the
popover background when it was a tooltip (white arrow and black popover
content).

However, the css adaptation was already present in `tooltip.scss` using
the css variable `--popover-arrow-color`, but the selector wasn't
correct since the arrow was always BEFORE the content.

This commit fixes the issue by placing the arrow after the popover
content.

task-3329927
Part of task-3326263

closes odoo/odoo#121975

X-original-commit: 0f1fb80ac6e36b8230ffaf3c7c2608d527b451a2
Signed-off-by: Pierre Paridans (app) <app@odoo.com>

addons/web/static/src/core/popover/popover.xml

@@ -3,8 +3,8 @@
 
     <t t-name="web.PopoverWowl" owl="1">
         <div role="tooltip" class="o_popover popover mw-100" t-att-class="props.class" t-ref="ref">
-            <div class="popover-arrow"/>
             <t t-slot="default" />
+            <div class="popover-arrow"/>
         </div>
     </t>