Set packer builder type with env variable

Set packer builder type with env variable

Using the -only CLI option for packer build does not work as
expected. The #CR 90dd675df482a8 (global-jjb) submitted with
common-packer v0.7.0 fails to build packer jobs because of a
bug in the packer build CLI.

The `-only` option packer build CLI does not set the cloud
provider name/type as per the documentation. The alternative
is to use an environment variable that is passed through the
packer job and can be reference in the packer templates.

The CR cc035619ac16 missed including the changes to the other
templates.

Issue: https://github.com/hashicorp/packer/issues/10495
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>
Change-Id: I14976aa77312a3d887d30b7d6e2cc32ab8073b72