test(e2e): create product per media test instead of hardcoded id [MPT-22436]

The media service fixtures built their service against the hardcoded
product id from e2e_config (catalog.product.id), which had reached its
maximum number of media items. MediaService.create then returned 400
Bad Request, failing setup for the sync and async media tests.

Point the sync and async media service fixtures at the shared
created_product / async_created_product fixtures so each run starts from
a freshly created, empty product instead of the shared seeded one.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: jentyk

tests/e2e/catalog/product/media/test_async_media.py

@@ -6,13 +6,13 @@
 
 
 @pytest.fixture
-def async_media_service(async_mpt_vendor, product_id):
-    return async_mpt_vendor.catalog.products.media(product_id)
+def async_media_service(async_mpt_vendor, async_created_product):
+    return async_mpt_vendor.catalog.products.media(async_created_product.id)
 
 
 @pytest.fixture
-def async_vendor_media_service(async_mpt_vendor, product_id):
-    return async_mpt_vendor.catalog.products.media(product_id)
+def async_vendor_media_service(async_mpt_vendor, async_created_product):
+    return async_mpt_vendor.catalog.products.media(async_created_product.id)
 
 
 @pytest.fixture

tests/e2e/catalog/product/media/test_sync_media.py

@@ -6,8 +6,8 @@
 
 
 @pytest.fixture
-def vendor_media_service(mpt_vendor, product_id):
-    return mpt_vendor.catalog.products.media(product_id)
+def vendor_media_service(mpt_vendor, created_product):
+    return mpt_vendor.catalog.products.media(created_product.id)
 
 
 @pytest.fixture