[FIX] web: add space above group separators

This commit reverts https://github.com/odoo/odoo/commit/0e0a2014b31e2fc6423e80971ac451a2dfe89de9

Before this commit, the string separator was too close to the
previous label/field.

We now have the same margins as in 15.3.

Steps to reproduce:
- Sales -> Orders -> customers
- Choose any
- Sales	& Purchase tab

closes odoo/odoo#102978

X-original-commit: 0510f5ed80bbffbee249e709d1df90192ee08f02
Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

addons/web/static/src/views/form/form_group/form_group.xml

@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
 
 <t t-name="web.Form.OuterGroup" owl="1">
-    <div class="o_group row align-items-start" t-attf-class="{{ allClasses }} {{ props.hasOuterTemplate and props.class ? '' : 'my-3' }}" t-att-style="props.style">
+    <div class="o_group row align-items-start" t-attf-class="{{ allClasses }}" t-att-style="props.style">
         <t t-slot="title" t-if="props.slots and props.slots.title" />
         <t t-foreach="getItems()" t-as="item" t-key="item_index">
             <span class="o_newline" t-if="item.newline" />

addons/web/static/src/views/view.scss

@@ -15,7 +15,3 @@
         box-shadow: 0 0 120px 100px #f9f9f9;
     }
 }
-
-.o_horizontal_separator:not(:first-child) {
-    margin-top: map-get($spacers, 4);
-}

addons/web/static/src/views/view_compiler.js

@@ -206,7 +206,7 @@ export function isTextNode(node) {
  */
 export function makeSeparator(title) {
     const separator = createElement("div");
-    separator.className = "o_horizontal_separator mb-3 text-uppercase fw-bolder small";
+    separator.className = "o_horizontal_separator mt-4 mb-3 text-uppercase fw-bolder small";
     separator.textContent = title;
     return separator;
 }