[centos] Add more RAM to avoid a crash of the VM during boot

This crash was witnessed for ppc64 with both CentOS 7 and 8

from_scratch/centos-base.yaml

@@ -30,6 +30,8 @@ global:
   installer_iso_finder_args: $${distrib} $${release_number} $${arch} $${mirror_base_url}
   qemu_iso_path: $${kameleon_cwd}/$${distrib}.iso
 
+  # If memory size is too low, the VM crashes.
+  qemu_memory_size: 2G
 
   base_kickstart_path: $${kameleon_data_dir}/kickstart/$${distrib}$${release_number}-ks.cfg
 

from_scratch/ppc64le/centos-base.yaml

@@ -30,6 +30,8 @@ global:
   installer_iso_finder_args: $${distrib} $${release_number} $${arch} $${mirror_base_url}
   qemu_iso_path: $${kameleon_cwd}/$${distrib}.iso
 
+  # If memory size is too low, the VM crashes.
+  qemu_memory_size: 2G
 
   base_kickstart_path: $${kameleon_data_dir}/kickstart/$${distrib}$${release_number}-ks.cfg