MPT-19657 fix unauthorized response in E2E tests (#253)

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Closes [MPT-19657](https://softwareone.atlassian.net/browse/MPT-19657)

- Updated E2E authorization test to expect "401 Authentication Failed"
error message instead of "401 Unauthorized" when validating responses
with invalid API tokens

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

[MPT-19657]:
https://softwareone.atlassian.net/browse/MPT-19657?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Author: d3rky

tests/e2e/test_access.py

@@ -8,7 +8,7 @@
 def test_unauthorised(base_url):
     client = MPTClient.from_config(api_token="TKN-invalid", base_url=base_url)  # noqa: S106
 
-    with pytest.raises(MPTHttpError, match=r"401 Unauthorized"):
+    with pytest.raises(MPTHttpError, match=r"401 Authentication Failed"):
         client.catalog.products.fetch_page()