CEC: Update the source LA in Vendor Commands tests Use the adapter's LA as the source address in the vendor command tests, instead of a hardcoded TV address. Bug: 251718681 Test: atest android.hdmicec.cts.common.HdmiCecVendorCommandsTest Change-Id: I87d3b2ca9f7a44e1226ac42de5f93940090ec5b9 (cherry picked from commit 0328412704e8d016ca430092436f60703d96d0e1)