chore: Fix ruff format violations in db_url_sanitisation_steps.py

Fix formatting issues detected by CI lint check:
- Simplify multi-line decorator arguments to single line
- Simplify multi-line assertion error messages to single line

This resolves the format --check failure blocking CI.

features/steps/db_url_sanitisation_steps.py

@@ -24,9 +24,7 @@ def step_db_url_given(context: Context, url: str) -> None:
     context.raw_db_url = url
 
 
-@given(
+@given('a mock settings object with database url "{db_url}"')
-    "a mock settings object with database url \"{db_url}\""
-)
 def step_mock_settings_with_db_url(context: Context, db_url: str) -> None:
     """Build a full mock Settings that ``build_info_data`` expects."""
     tmpdir = mkdtemp()
@@ -77,17 +75,11 @@ def step_call_build_info(context: Context) -> None:
 def step_assert_sanitised_url(context: Context, expected: str) -> None:
     """Verify the sanitised URL matches expectation."""
     actual = context.sanitised_url
-    assert actual == expected, (
+    assert actual == expected, f"Expected '{expected}', got '{actual}'"
-        f"Expected '{expected}', got '{actual}'"
-    )
 
 
-@then(
+@then('the database field in info data should be "{expected}"')
-    "the database field in info data should be \"{expected}\""
-)
 def step_assert_info_db_field(context: Context, expected: str) -> None:
     """Verify the sanitised URL appears correctly in build_info_data output."""
     actual = context.info_data["database"]
-    assert actual == expected, (
+    assert actual == expected, f"Expected database field '{expected}', got '{actual}'"
-        f"Expected database field '{expected}', got '{actual}'"
-    )