test(a2a): cover input_required and auth_required as non-terminal states

[vishal-bulbule]

Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• N/A

2. Or, if no issue exists, describe the change:

This is the follow-up test a maintainer asked for in
#6872:
"input_required and auth_required still aren't covered by tests, so a small pull request for
those is welcome."

Problem:

aef3a9c set skip_summarization for terminal A2A task states (completed, failed, canceled).
The tests for non-terminal states covered only submitted and working, so nothing checked
that input_required and auth_required, which pause a task for the user, do not mark the
converted event as a final response.

Solution:

Add TS_INPUT_REQUIRED and TS_AUTH_REQUIRED to the existing
test_convert_a2a_task_to_event_non_terminal_state_does_not_set_skip_summarization
parametrization in both tests/unittests/a2a/converters/test_to_adk.py and
tests/unittests/a2a/converters/test_event_converter.py. Test-only change.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

The new cases pass on main, and fail if either state is treated as terminal in
to_adk_event.py / event_converter.py (checked by temporarily adding them to the terminal
set):

$ pytest tests/unittests/a2a/converters -k non_terminal_state
8 passed
(with input_required/auth_required added to the terminal set: 4 failed, 4 passed)

$ pytest tests/unittests/a2a tests/unittests/integrations/agent_registry/test_agent_registry.py  (a2a-sdk 0.3.26)
807 passed

$ pytest tests/unittests -n auto
15291 passed, 1 failed

$ tox   (Python 3.10, 3.11, 3.12, 3.13, 3.14)
py310: 15225 passed, 1 failed
py311: 15234 passed, 1 failed
py312: 15225 passed, 1 failed
py313: 15225 passed, 1 failed
py314: 15225 passed, 1 failed

The one failing test below, test_import_loading.py::test_entry_point_loads_only_allowlisted_packages[agent],
also fails on main (d57c84f) and is unrelated to this change; #7214 fixes it.

Manual End-to-End (E2E) Tests:

N/A, test-only change.

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas. (N/A, test-only)
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end. (N/A, test-only)
• Any dependent changes have been merged and published in downstream modules. (N/A)