DAG Import Errors message is dangling in web-interface

### Apache Airflow version Other Airflow 2 version (please specify below) ### If "Other Airflow 2 version" selected, which one? 2.10.2 ### What happened? <img width="420" alt="dag_report_error" src="https://github.com/user-attachments/assets/fc99412d-7ca8-4308-88b1-cd568594846e" /> We have this message in the Airflow's web-interface no matter what. This DAG can exist or not - the error still shows. We have found many different topics across the Internet for various Airflow versions. Some of them from 2018. So users constantly witness these dangling messages, but there are no clarification for this case. Also we don't have an understanding what is a source for this notification message. It sits in the Airflow DB and webserver is selecting it from there or other core components are generating it for webserver somehow. ### What you think should happen instead? Even though the error message itself is far from perfect, we expect that if DAG doesn't exist anymore, the error message should disappear. ### How to reproduce We use gitsync option for storing DAGs: ````yaml # DAGs Config dags: gitSync: enabled: true repo: "https://my.repo/path/name.git" branch: "master" rev: "HEAD" subPath: "airflowk8s/dags" credentialsSecret: my-secret period: 5s maxFailures: 10 ```` And our DAG is just script.py like that, nothing complicated: `print("D0ne!")` So I guess steps should be: 1) Create a broken DAG in remote repository; 2) Get the error message in the Airflow's web-interface; 3) Delete a broken DAG in remote repository; 4) Wait for your gitsync; 5) The error message in the Airflow's web-interface will dangle. But this bug appears randomly, so we don't know exact reason. ### Operating System Kubernetes v1.31.0-eks ### Versions of Apache Airflow Providers _No response_ ### Deployment Official Apache Airflow Helm Chart ### Deployment details _No response_ ### Anything else? _No response_ ### Are you willing to submit PR? - [ ] Yes I am willing to su…