CLI JSON output is polluted by logs and cannot be parsed by jq

### Under which category would you file this issue? Airflow Core ### Apache Airflow version 3.2.0 ### What happened and how to reproduce it? ## Issue Description When running an Airflow CLI command with JSON output, logs are printed before the JSON payload. For example: ```bash airflow dags list -o json prints Airflow/Alembic log lines before the JSON array starts. This makes the output invalid JSON and breaks standard command-line tools such as jq. ## Steps to reproduce 1. Run: airflow dags list -o json 2. Try to parse the output with jq: airflow dags list -o json | jq 3. Or redirect the output to a file: airflow dags list -o json > /tmp/output.json 2>&1 head -10 /tmp/output.json ## Observed behavior The command outputs log lines before the JSON content, for example: 2026-04-30T01:14:29.770306Z [info] setup plugin alembic.autogenerate.schemas 2026-04-30T01:14:29.770491Z [info] setup plugin alembic.autogenerate.tables 2026-04-30T01:14:29.922347Z [warning] Could not import graphviz... [{"dag_id": "SAFE_MODE_TEST_66104", ...}] Because the output does not start with valid JSON, parsing fails: jq: parse error: Invalid numeric literal at line 1, column 14 The failed pipe can also produce a Python BrokenPipeError traceback. ##Screenshots ##JSON parsing failure with jq <img width="921" height="723" alt="Image" src="https://github.com/user-attachments/assets/652702b7-1e86-4c6c-a592-be8217e6e73f" /> ##Raw JSON output polluted by logs <img width="918" height="806" alt="Image" src="https://github.com/user-attachments/assets/7a0ae3d9-2dac-4755-8899-5cf89b3dbc3a" /> ##Redirected output file starts with logs instead of JSON <img width="937" height="860" alt="Image" src="https://github.com/user-attachments/assets/b537d35d-bf4a-48ae-8c07-d4276c2ca6e3" /> ### What you think should happen instead? When using `-o json`, the command output should be valid JSON that can be parsed directly by tools such as `jq`. Logs and warnings should not be written to the same output stream as the JSO…