[IMP] sale: rename variables in variant_templates
[IMP] sale: rename variables in variant_templates

To follow the naming convention used in the rest of the code.

- `variant_id` (which made no sense in this case) -> `ptal`
- `value_id` -> `ptav`

Split commit to make the diff of a following PR easier to read.

Part of task-1912579

closes odoo/odoo#35865

Signed-off-by: Sébastien Theys (seb) <62d754cc350e84d3b1c32ae79f976f5348e74a40@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo