SQLAlchemy engine configuration is not passed to FAB based UI. Faced this issue when running Airflow with MySQL metadata store with wait_timeout = 120. Webserver is failing with Internal Server Error due to "[MySQL Server has gone away](https://docs.sqlalchemy.org/en/13/faq/connections.html#mysql-server-has-gone-away)" error. Settings like `sql_alchemy_pool_recycle` and  `sql_alchemy_pool_pre_ping` have no impact on FAB internal communication with MySQL.

**Apache Airflow version**: 1.10.12
airflow/settings.py
HEADER = '\n'.join([
    r'  ____________       _____________',
    r' ____    |__( )_________  __/__  /________      __',
    r'____  /| |_  /__  ___/_  /_ __  /_  __ \_ | /| / /',
    r'___  ___ |  / _  /   _  __/ _  / / /_/ /_ |/ |/ /',
    r' _/_/  |_/_/  /_/    /_/    /_/  \____/____/|__/',
])
LOGGING_LEVEL = logging.INFO
GUNICORN_WORKER_READY_PREFIX = "[ready] "
LOG_FORMAT = conf.get('logging', 'log_format')
SIMPLE_LOG_FORMAT = conf.get('logging', 'simple_log_format')
SQL_ALCHEMY_CONN: Optional[str] = None
PLUGINS_FOLDER: Optional[str] = None
LOGGING_CLASS_PATH: Optional[str] = None
DAGS_FOLDER: str = os.path.expanduser(conf.get('core', 'DAGS_FOLDER'))
engine: Optional[Engine] = None
Session: Optional[SASession] = None
json = json  
STATE_COLORS = {
    "queued": "gray",
    "running": "lime",
    "success": "green",
    "failed": "red",
    "up_for_retry": "gold",
    "up_for_reschedule": "turquoise",
    "upstream_failed": "orange",
    "skipped": "pink",
    "scheduled": "tan",
}
def policy(task):