Use default disk image size for centos/7

Latest centos/7 image from atlas now comes with 40 GB disk size which
is equal to the virtual_size we specify in the Vagrantfile.  Libvirt
provider doesn't like it and produces an ugly stacktrace.

The new default value now sufficient run kolla properly and we can
remove the code that artificially increased the disk size.

Change-Id: I7a645543cfcc027b4a3e0d02d8e7f436d8410ec5
Backport: Liberty
Closes-Bug: #1511265

dev/vagrant/Vagrantfile

@@ -93,12 +93,6 @@ Vagrant.configure(2) do |config|
     admin.vm.synced_folder ".", get_default(:vagrant_shared_folder), disabled: true
     admin.vm.provider PROVIDER do |vm|
       vm.memory = MULTINODE ? 1024 : 4096
-      if PROVIDER == 'libvirt'
-        # This only works with libvirt provider.
-        # We should be able to do something similar for virtualbox
-        # http://askubuntu.com/questions/317338/how-can-i-increase-disk-size-on-a-vagrant-vm
-        vm.machine_virtual_size = 40
-      end
     end
     admin.hostmanager.aliases = "operator"
   end

dev/vagrant/bootstrap.sh

@@ -66,24 +66,6 @@ EOF
     usermod -aG docker vagrant
 }
 
-function resize_partition {
-    fdisk /dev/vda <<EOF
-n
-p
-
-
-t
-
-8e
-w
-EOF
-    partprobe
-    pvcreate /dev/vda4
-    vgextend VolGroup00 /dev/vda4
-    lvextend /dev/VolGroup00/LogVol00 /dev/vda4
-    resize2fs /dev/VolGroup00/LogVol00
-}
-
 function configure_kolla {
     # Use local docker registry
     sed -i -r "s,^[# ]*namespace.+$,namespace = ${REGISTRY}/lokolla," /etc/kolla/kolla-build.conf
@@ -155,6 +137,5 @@ prep_work
 install_docker
 
 if [ "$1" = "operator" ]; then
-    resize_partition
     configure_operator
 fi