Cannot exec certain QMP guest commands using unix socket but Virsh can
Description of problem:
There are two channels configured to communicate the guest. 
 - a) qemu.guest_agent.0
 - b) unix socket: -qmp unix:/tmp/qmp_win7-101.sock,server,nowait


**For unix socket connection, certain commands like ```guest-info``` and other guest functions are missing.** However, invoking guest-xx functions successfully in Virsh (through qemu.guest_agent.0).
Steps to reproduce:
```
$sudo socat unix-connect:/tmp/qmp_win7-101.sock readline
{"QMP": {"version": {"qemu": {"micro": 0, "minor": 2, "major": 4}, "package": "qemu-kvm-4.2.0-59.module_el8.5.0+1063+c9b9feff.1"}, "capabilities": ["oob"]}}

{"execute":"qmp_capabilities"}
{"return": {}}

{"execute": "guest-info"}
{"error": {"class": "CommandNotFound", "desc": "The command guest-info has not been found"}}
```

I checked ```/etc/sysconfig/qemu-ga``` and unmarked blacklist functions, but it did not solve this problem.
```
# original contents of qemu-ga
#BLACKLIST_RPC=guest-file-open,guest-file-close,guest-file-read,guest-file-write,guest-file-seek,guest-file-flush,guest-exec,guest-exec-status
```