Improving webserver code coverage of utils.py

[lh5844]

Improved code coverage of utils.py in the webserver to 88% which improved overall code coverage of the webserver to 80%

The following images are captured after running python scripts/cov/www_coverage.py

related: #35127

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[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide (https://github.com/apache/airflow/blob/main/contributing-docs/README.rst)
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[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.