The name of the zone group. For example:
Availability Zones - us-east-1-zg-1
us-east-1-zg-1
Local Zones - us-west-2-lax-1
us-west-2-lax-1
Wavelength Zones - us-east-1-wl1-bos-wlz-1
us-east-1-wl1-bos-wlz-1