[IMP] website_*: uniformize pager position on center

Before this commit, the pager was on the left or centered.
Now, it is always centered regardless of the website pages (portal or
not).

closes odoo/odoo#97967

Related: odoo/enterprise#30343
Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

addons/portal/views/portal_templates.xml

@@ -213,7 +213,7 @@
                 <t t-out="0"/>
             </table>
         </div>
-        <div t-if="pager" class="o_portal_pager text-center">
+        <div t-if="pager" class="o_portal_pager d-flex justify-content-center">
             <t t-call="portal.pager"/>
         </div>
     </template>

addons/website/views/website_templates.xml

@@ -2421,7 +2421,7 @@ Sitemap: <t t-esc="url_root"/>sitemap.xml
                         </tbody>
                     </table>
                 </div>
-                <div t-if="pager" class="o_portal_pager text-center">
+                <div t-if="pager" class="o_portal_pager d-flex justify-content-center">
                     <t t-call="website.pager"/>
                 </div>
             </div>
@@ -2458,7 +2458,7 @@ Sitemap: <t t-esc="url_root"/>sitemap.xml
                 <div t-if="results" class="table-responsive">
                     <t t-call="website.one_hybrid" t-foreach="results" t-as="result"/>
                 </div>
-                <div t-if="pager" class="o_portal_pager text-center">
+                <div t-if="pager" class="o_portal_pager d-flex justify-content-center">
                     <t t-call="website.pager"/>
                 </div>
             </div>