[FIX] theme_cobalt, theme_paptic: restore proper asset order

Error made during migration of assets, those files became prepend to
the bundle instead of append to... hopefully these are the only ones.

Part of https://github.com/odoo/design-themes/pull/2
task-2491890

X-original-commit: 1fe3c6aecc

theme_cobalt/data/ir_asset.xml

@@ -6,7 +6,6 @@
             <field name="key">theme_cobalt.primary_variables_scss</field>
             <field name="name">Primary variables SCSS</field>
             <field name="bundle">web._assets_primary_variables</field>
-            <field name="directive">prepend</field>
             <field name="path">theme_cobalt/static/src/scss/primary_variables.scss</field>
         </record>
 

theme_paptic/data/ir_asset.xml

@@ -6,7 +6,6 @@
             <field name="key">theme_paptic.primary_variables_scss</field>
             <field name="name">Primary variables SCSS</field>
             <field name="bundle">web._assets_primary_variables</field>
-            <field name="directive">prepend</field>
             <field name="path">theme_paptic/static/src/scss/primary_variables.scss</field>
         </record>