1500ms as EXTRA_PROBING_TIME_MSECS not always enough

In slow systems running openwrt, without udev events, the reporting of new ports may take a long time to complete, especially during initial daemon boot as it needs to process the cached events that happened before the daemon was started.

This may lead to modem objects created with a subset of available ports, and in the worst case we may end up creating unusable modems without control ports. Some other times we may be ignoring the QMI+NET ports and creating AT-only modems, which is equally not desirable.

Updating EXTRA_PROBING_TIME_MSECS would solve the problem, but we cannot change that by default for all setups as it would impose an extra wait time in systems which don't really require it. A good compromise could be to increase this value for openwrt systems and only during the daemon startup phase, and keep the old value otherwise.

See https://lists.freedesktop.org/archives/modemmanager-devel/2022-January/009096.html