fix: handle PermissionError in init_log_folder for mounted filesystems

[Pranaykarvi]

Problem

init_log_folder() iterates through all parent directories from / calling mkdir() on each. For paths on mounted filesystems (e.g. /mnt/nfs-share/airflow/logs), this calls mkdir('/mnt') and mkdir('/mnt/nfs-share') which fails with PermissionError because the Airflow user cannot create system-level directories. exist_ok=True only suppresses FileExistsError, not PermissionError, crashing all Airflow CLI commands including airflow db migrate.

Fix

• Replaced the explicit parent loop in init_log_folder() with Path.mkdir(parents=True, exist_ok=True) which only creates directories that don't already exist, stopping at the first existing parent
• Wrapped the call in try/except (PermissionError, OSError) to log a warning instead of crashing
• Wrapped the init_log_folder() call in configure_logging() with the same try/except so CLI commands continue even if the log folder cannot be created

Fixes #63863