Update promotions applicator to use product instead of promo IDs

This change modifies the test cases to pass the product object directly to the `apply` method of `RuntimePromotionsApplicator` instead of an array of promotion identifiers. It ensures consistency with the expected method signature and aligns the tests with the updated behavior.

Author: loevgaard

tests/Calculator/ProductVariantPricesCalculatorTest.php

@@ -69,7 +69,7 @@ public function it_calculates_catalog_promotion(): void
         $productVariant->getProduct()->willReturn($product->reveal());
 
         $runtimePromotionsApplicator = $this->prophesize(RuntimePromotionsApplicatorInterface::class);
-        $runtimePromotionsApplicator->apply(['promo1', 'promo2'], 800, true)->willReturn(600);
+        $runtimePromotionsApplicator->apply($product->reveal(), 800, true)->willReturn(600);
 
         $calculator = new ProductVariantPricesCalculator($runtimePromotionsApplicator->reveal());
 
@@ -103,7 +103,7 @@ public function it_respects_minimum_price(): void
         $productVariant->getProduct()->willReturn($product->reveal());
 
         $runtimePromotionsApplicator = $this->prophesize(RuntimePromotionsApplicatorInterface::class);
-        $runtimePromotionsApplicator->apply(['promo1'], 800, false)->willReturn(600);
+        $runtimePromotionsApplicator->apply($product->reveal(), 800, false)->willReturn(600);
 
         $calculator = new ProductVariantPricesCalculator($runtimePromotionsApplicator->reveal());