Bug: error 400 when setting pool on a Qemu Guest

[Tinyblargon]

Telmate/terraform-provider-proxmox#918

This shouldn't add the pool parameter:

proxmox-api-go/proxmox/config_qemu.go

Lines 369 to 371 in 586199e

	if config.Pool != "" {
	params["pool"] = config.Pool
	}

Also in proxmox 8 you can add guests to a pool when they are already member of a pool.
For now we would go with the proxmox 7 workflow.