[FIX] website: oe_no_empty only in edit mode

Test case;
The user as edition rights on the website
Install quotation builder
Have a sale order with many lines
Click preview > you end up on the portal view

Before this commit, there was a blank space just before the
sale order lines per se
This was because the sale order's lines website description
were in the dom and took some fixed space, which is a feature
meant for the edit mode by using the class oe_no_empty

After this commit, we restrict the effect of that class concerning
the fixed height only to edit mode
There is no more gaps in the sale order preview

In master, one should check whether the class / rule is still relevant

OPW 2082267

closes odoo/odoo#38435

X-original-commit: 4b177412235cdf3e62f5ff30c18246c003c25cc2
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>

addons/website/static/src/scss/website.edit_mode.scss

@@ -78,7 +78,8 @@ $-editor-messages-margin-x: 2%;
     display: block!important;
 }
 
-[data-oe-type=html].oe_no_empty:empty {
+// TODO: in master check if the class / rule is relevant at all
+.editor_enable [data-oe-type=html].oe_no_empty:empty {
     height: 16px!important;
 }