The database has uses beyond the webmap.
Cf. ca91a579770c89d25aefae220079bf336fa88dc9 in tools.

This is needed for systemd/journal.py.

    --- Logging error ---
    Traceback (most recent call last):
      File "/usr/lib/python3/dist-packages/systemd/journal.py", line 617, in emit
        self.send(msg,
      File "/usr/lib/python3/dist-packages/systemd/journal.py", line 466, in send
        return sendv(*args)
               ^^^^^^^^^^^^
    OSError: [Errno 97] Address family not supported by protocol
    Call stack:
      File "/usr/local/bin/webmap-import", line 814, in <module>
        main()
      File "/usr/local/bin/webmap-import", line 679, in main
        processRaster(layername, layerdef,
      File "/usr/local/share/webmap/export_raster.py", line 84, in processRaster
        logging.info('Output directory "%s" is up to date, skipping', str(dst))
      File "/usr/lib/python3.11/logging/__init__.py", line 2148, in info
        root.info(msg, *args, **kwargs)
      File "/usr/lib/python3.11/logging/__init__.py", line 1489, in info
        self._log(INFO, msg, args, **kwargs)
      File "/usr/lib/python3.11/logging/__init__.py", line 1634, in _log
        self.handle(record)
      File "/usr/lib/python3.11/logging/__init__.py", line 1644, in handle
        self.callHandlers(record)
      File "/usr/lib/python3.11/logging/__init__.py", line 1706, in callHandlers
        hdlr.handle(record)
      File "/usr/lib/python3.11/logging/__init__.py", line 978, in handle
        self.emit(record)
      File "/usr/lib/python3/dist-packages/systemd/journal.py", line 627, in emit
        self.handleError(record)
    Message: 'Output directory "%s" is up to date, skipping'
    Arguments: ('/var/www/webmap/raster/kskog',)

Cf. systemd.exec(5).

We also lower tile expiration time from 8h to 30m to reduce the race
condition where the database an the on-disk tiles are not in sync.