Fixes for opteetest/xtest qemu hang in "make test", changes to qemu CPU type and default tune

Major changes in CPU tuning and qemu config too. Relates to poky fixes to oeqa runtime test framework https://lists.openembedded.org/g/openembedded-core/message/176919 which did not correctly time out test commands when qemu system hangs, but these poky changes are not needed when workarounds from these changers are in place.