tests: convert x86_64 tests to query-cpus-fast

tests: convert x86_64 tests to query-cpus-fast

All supported versions of QEMU include the query-cpus-fast QMP command.
In preparation for dropping support for the old "query-cpus" commands,
convert the JSON output for x86 tests to the new format, and drop the
"halted" field from the expected output as it is not available anymore.

The CPU properties were obtained from the query-hotpluggable-cpus output
in tests/qemumonitorjsondata.  CPU, thread_id, and qom_path are renamed
respectively to cpu-index, qom-path and thread-id, while nip and halted
are removed.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>