[test][python] Fix Action deserialize tests on release branch

[wenjin272]

What changed

• Update two Action config deserialization test fixtures to use the
  release-0.3 field name, listen_event_types.

Why

PR #921 was authored against main, where the field is named
trigger_conditions. When that change was cherry-picked to release-0.3, the
new tests retained the main field name even though Action on the release
branch still accepts listen_event_types.

As a result, all Python unit-test matrix jobs failed before exercising the
intended config deserialization behavior:

TypeError: Action.__init__() got an unexpected keyword argument 'trigger_conditions'

This keeps the production implementation unchanged and adapts only the
branch-specific test fixtures.

Validation

• python/.venv/bin/python -m pytest flink_agents/plan/tests/test_action.py -q
  • 7 passed
• Full non-integration Python unit-test selection
  • 571 passed, 11 skipped, 122 deselected
• ruff check and ruff format --check on the changed file
• git diff --check