[FIX] mrp: add indexes on highly search fields

Add two indexes (on `product_id` and `product_tmpl_id`)
on the `mrp.bom` model to speed up `_bom_find`
which is highly used and it uses always the `product_tmpl_id` and
sometime the `product_id` in the search domain.

Performance Gain:
With a DB with 2K BoM, a `_bom_find` search (`product_id` and
`product_tmpl_id` are in domain): The SQL execution time
is +- 5 times faster.

task-2390516

closes odoo/odoo#64934

X-original-commit: 64861aed03b616820d717bc08e7c38c56145e0f2
Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>

addons/mrp/models/mrp_bom.py

@@ -31,11 +31,11 @@ class MrpBom(models.Model):
         default='normal', required=True)
     product_tmpl_id = fields.Many2one(
         'product.template', 'Product',
-        check_company=True,
+        check_company=True, index=True,
         domain="[('type', 'in', ['product', 'consu']), '|', ('company_id', '=', False), ('company_id', '=', company_id)]", required=True)
     product_id = fields.Many2one(
         'product.product', 'Product Variant',
-        check_company=True,
+        check_company=True, index=True,
         domain="['&', ('product_tmpl_id', '=', product_tmpl_id), ('type', 'in', ['product', 'consu']),  '|', ('company_id', '=', False), ('company_id', '=', company_id)]",
         help="If a product variant is defined the BOM is available only for this product.")
     bom_line_ids = fields.One2many('mrp.bom.line', 'bom_id', 'BoM Lines', copy=True)