[FIX] theme_*: fix font style of snippet headers

Some snippets contain incorrect font style that are not achievable using
the editor (for example: <h2 class="display-3"> in the "Key benefits"
snippet).

These snippets were adapted in the community commit linked to this one
to align with what the editor would generate if we recreated them from
scratch.

In this commit, we adapt the themes following the change in community.
We also fix a few issues (e.g., wording for the ´s_numbers´ snippet)
noticed during the changes.

task-4148057

closes odoo/design-themes#895

Related: odoo/odoo#178957
Signed-off-by: Robin Lejeune (role) <role@odoo.com>

theme_bookstore/views/snippets/s_numbers.xml

@@ -12,14 +12,20 @@
         <div class="o_we_shape o_web_editor_Floats_12"/>
     </xpath>
     <!-- Titles -->
-    <xpath expr="//h6" position="replace" mode="inner">
-        Useful options
+    <xpath expr="//span[hasclass('h5-fs')]" position="replace" mode="inner">
+        Unique references
     </xpath>
-    <xpath expr="//h6" position="replace" mode="inner">
-        Beautiful snippets
+    <xpath expr="(//span[hasclass('s_number')])[2]" position="replace" mode="inner">
+        98%
     </xpath>
-    <xpath expr="//h6" position="replace" mode="inner">
-        Amazing pages
+    <xpath expr="(//span[hasclass('h5-fs')])[2]" position="replace" mode="inner">
+        Happy customers
+    </xpath>
+    <xpath expr="(//span[hasclass('s_number')])[3]" position="replace" mode="inner">
+        418
+    </xpath>
+    <xpath expr="(//span[hasclass('h5-fs')])[3]" position="replace" mode="inner">
+        Stores around the world
     </xpath>
 </template>