Clean up unneeded unique() calls on ORM

### Body Similar to #43064. Maybe there are more to be had? cc @dstandish I can find 6 with a naive text search in main, 4 in main and 2 in providers. We should review them individually. https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/airflow/assets/manager.py#L161-L167 https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/airflow/dag_processing/collection.py#L64-L75 https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/airflow/jobs/scheduler_job_runner.py#L1327-L1338 https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/airflow/www/views.py#L1000-L1006 https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/providers/src/airflow/providers/fab/auth_manager/api_endpoints/role_and_permission_endpoint.py#L88-L92 https://github.com/apache/airflow/blob/e20146d44b340f719f7fb432f93741e011690558/providers/src/airflow/providers/fab/auth_manager/security_manager/override.py#L2792-L2799 (There is a 7th `unique()` match in a Jinja2 template.) ### Committer - [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.