[FIX] website_blog: do not preview "number of blog posts" options
[FIX] website_blog: do not preview "number of blog posts" options

Only re-render with the chosen number on click, not on hover.

Part of https://github.com/odoo/odoo/pull/36803
task-2070930
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo