Feat: Rewrite packer jobs to work with hcl2 format

Feat: Rewrite packer jobs to work with hcl2 format

Rewrite packer jobs to work with HCL2 format.

As of packer version 1.7.0 HCL2 is the preferred way to write Packer
templates. HCL2 preserves existing workflows while leveraging HCL2’s
advanced features like variable interpolation and configuration
composability.

Upgrade packer version to v1.9.1. JSON format templates are
deprecated and no longer work with packer version > 1.9.x.
Project specific templates require to be upgraded to HCL2 format.

Support for '.json' templates will be removed from common-packer in
subsequent releases. Therefore, the jobs are expected to work with
older templates.

Ref: https://gerrit.linuxfoundation.org/infra/c/releng/common-packer/+/71859
Issue: RELENG-4764
Change-Id: Ie591343ac87caca217ff7125a84f4b769bb3a40c
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>