Fix BigQuery private-cloud trigger result payloads

[cursor]

Fix private-cloud BigQuery deferrable trigger result payloads.

Bug and impact:

• In non-default Google Cloud universes, BigQueryGetDataTrigger and BigQueryIntervalCheckTrigger use the synchronous BigQuery hook to fetch query results.
• That hook returns dict rows containing native Python values such as Decimal and date.
• BigQueryGetDataTrigger returned those dictionaries directly even when as_dict=False, breaking the documented list-of-lists contract, and both triggers could emit values that fail triggerer IPC serialization after the external BigQuery job had already completed.

Root cause:

• The private-cloud path bypassed the async REST result conversion used by the default-universe path, so it did not normalize row shape or convert native BigQuery client values into trigger-safe values.

Fix:

• Normalize private-cloud synchronous BigQuery rows in the trigger before yielding TriggerEvent payloads.
• Preserve as_dict=True vs as_dict=False output shape for BigQueryGetDataTrigger.
• Convert non-primitive result values to trigger-safe representations, including base64 for bytes and ISO strings for date/time values.
• Cover the regression with focused unit tests using Decimal and date row values.

Validation:

• uvx ruff format providers/google/src/airflow/providers/google/cloud/triggers/bigquery.py providers/google/tests/unit/google/cloud/triggers/test_bigquery.py
• uvx ruff check --fix providers/google/src/airflow/providers/google/cloud/triggers/bigquery.py providers/google/tests/unit/google/cloud/triggers/test_bigquery.py
• uv run --project providers/google --no-dev --with pytest --with pytest-asyncio --with-editable ./devel-common pytest providers/google/tests/unit/google/cloud/triggers/test_bigquery.py::TestBigQueryGetDataTrigger::test_bigquery_get_data_trigger_success_with_data_custom_universe providers/google/tests/unit/google/cloud/triggers/test_bigquery.py::TestBigQueryIntervalCheckTrigger::test_interval_check_trigger_success_non_default_universe -xvs (3 passed)

Notes:

• The standard uv run --project providers/google pytest ... setup failed in this image before tests because provider dev extras attempted to build mysqlclient without MySQL/MariaDB pkg-config libraries.
• The Breeze fallback could not run because Docker is not installed in this automation image.

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Was generative AI tooling used to co-author this PR?

• Yes — GPT-5.5

Generated-by: GPT-5.5 following the guidelines

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