During the v4l_uvc_device constructor it would call foreach_uvc_device in order to check if the constructed device is still connected.

It is very inefficient to search all devices to do find if 1 device is within the list.
This problem is them squared by the number of devices.

In this pr I have removed the check all together, as it is unlikely a newly found device would not be connected.

For the curious, I followed the source of why foreach_uvc_device is slow on high device count systems (>24).
It appears get_dev_capabilities tends too take up to 100ms on several open(/dev/videoXXX) calls, causing the total time of foreach_uvc_device to balloon out to ~3s.

Another note is that udev_device_watcher also lists devices on creation. Since this is a singleton its only called once. But it may be more efficient to use this cache for query_devices instead of calling direct to the source /dev/videoXXX, although potentially less accurate.