[FIX] web: Remove CSS comment parsed as rule

A CSS comment in webclient_templates was written as a JS comment and
appeared as an invalid CSS rule in the devtools. This commit converts
that comment to use the proper syntax.

closes odoo/odoo#94925

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web/views/webclient_templates.xml

@@ -190,7 +190,7 @@
         <t t-call-assets="web.tests_assets" t-js="False"/>
         <style>
             body {
-                position: relative; // bootstrap-datepicker needs this
+                position: relative; /* bootstrap-datepicker needs this */
             }
             body:not(.debug) .modal-backdrop, body:not(.debug) .modal, body:not(.debug) .ui-autocomplete {
                 opacity: 0 !important;