Fix the API server silently ignoring its gunicorn worker hooks

[FrankYang0529]

Why

• create_gunicorn_app() puts "config": "python:airflow.api_fastapi.gunicorn_config" into the options dict, but nothing reads it. only The cfg.config is only read by Application.load_config(), but AirflowGunicornApp inherits BaseApplication.

How

• Pass the two hooks as callables in the options dict. gunicorn's hook settings are type = callable, so cfg.set() on them takes effect directly.

Verification

• uv run --project airflow-core pytest airflow-core/tests/unit/cli/commands/test_gunicorn_monitor.py -q

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

• Yes - Claude Code

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