CAN test failures on CI systems with hardware CAN devices

Some of the pyagl CAN tests fail on e.g. the AGL reference hardware board in CI, as the hardware CAN devices are not connected to anything.  This means the CAN binding cannot successfully open the configured can0 device since it is not "up", and a bunch of tests that expect a working system fail.  The proposed workaround is to change the CAN binding device mapping configuration in CI builds to use vcan0, which the existing helper logic will automatically bring up before the binding starts.