Add JWT issuer config to docker-compose and breeze environment

[choo121600]

Add AIRFLOW__API_AUTH__JWT_ISSUER configuration to docker-compose.yaml and breeze shell environment for consistent JWT authentication.

Why

After #61278 , the JWT tokens omit the iss claim when issuer is unset, causing authentication failures in E2E tests.

Change

• airflow-core/docs/howto/docker-compose/docker-compose.yaml: Add AIRFLOW__API_AUTH__JWT_ISSUER environment variable
• dev/breeze/src/airflow_breeze/params/shell_params.py: Add AIRFLOW__API_AUTH__JWT_ISSUER to breeze environment setup

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• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
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[potiuk]

Nice!

[github-actions]

Backport failed to create: v3-1-test. View the failure log Run details

Status	Branch	Result
❌	v3-1-test

You can attempt to backport this manually by running:

cherry_picker c3b5c66 v3-1-test

This should apply the commit to the v3-1-test branch and leave the commit in conflict state marking
the files that need manual conflict resolution.

After you have resolved the conflicts, you can continue the backport process by running:

cherry_picker --continue

If you don't have cherry-picker installed, see the installation guide.