CEC: Regression fix in the CecPortDiscoverer class.

When cec-client is unavailable throw CecPortBusyExcception.

When a parallel cec-client instance is present, it takes more than 10s
to print "unable to open the device on port". Resolving it by increasing
timeout.

In case when vendor command message is not found, move to the next port.

When a port is already mapped to some device, remove the port from
launchCommand before moving to another port.

Remove port from launchCommand only after all the retries are done, not
before that.

Bug: 185454274
Test: atest CtsHdmiCecHostTestCases
Change-Id: I00d3149cf685bfcd34ae6179462e1e81a31d7f00