fix(tests): remove duplicate "rejection output should contain" step to fix AmbiguousStep

The new step file defined a Then step that collided with the pre-existing
definition in validation_attach_type_guard_steps.py:220, causing behave to
abort step-module loading with AmbiguousStep across every worker and
failing the unit_tests gate with 32 errored features.

Remove the duplicate from the new file and bridge context.last_result =
context.named_opts_result after each invoke so the pre-existing,
context.last_result-based step covers the new feature file's scenarios.

Closes #3684

features/steps/tdd_validation_attach_named_options_steps.py

@@ -80,6 +80,7 @@ def step_named_opts_invoke_with_args(
         validation_app,
         cmd,
     )
+    context.last_result = context.named_opts_result
 
 
 @when('I invoke validation attach "{resource}" "{validation}" with no extra args')
@@ -92,6 +93,7 @@ def step_named_opts_invoke_no_args(
         validation_app,
         cmd,
     )
+    context.last_result = context.named_opts_result
 
 
 # ---------------------------------------------------------------------------
@@ -163,10 +165,3 @@ def step_named_opts_attach_rejected(context: Context) -> None:
         f"Expected non-zero exit code (rejection), got {result.exit_code}. "
         f"Output: {result.output}"
     )
-
-
-@then('the rejection output should contain "{text}"')
-def step_named_opts_rejection_contains(context: Context, text: str) -> None:
-    """Verify the rejection output contains the expected text."""
-    output = context.named_opts_result.output
-    assert text in output, f"Expected {text!r} in rejection output, got: {output!r}"