[FEATURE REQUEST] Update OS cloud images to the latest

[to-bar]

Is your feature request related to a problem? Please describe.
Update Ubuntu 18.04-LTS/RHEL 7/CentOS 7 images used in the cloud to the latest version before releasing v1.2.0.

Describe the solution you'd like
Update Azure DevOps pipelines, documentation and epicli defaults.

Some files to be updated:

Azure:
https://github.com/epiphany-platform/epiphany/blob/develop/core/src/epicli/data/azure/defaults/infrastructure/virtual-machine.yml
https://github.com/epiphany-platform/epiphany/blob/develop/core/src/epicli/data/azure/defaults/infrastructure/cloud-os-image-defaults.yml

AWS:
https://github.com/epiphany-platform/epiphany/blob/develop/core/src/epicli/data/aws/defaults/infrastructure/virtual-machine.yml
https://github.com/epiphany-platform/epiphany/blob/develop/core/src/epicli/data/aws/defaults/infrastructure/cloud-os-image-defaults.yml

Additional context
n/a

---

DoD checklist

• Changelog updated
• COMPONENTS.md updated / doesn't need to be updated
• Schema updated / doesn't need to be updated
• Feature has automated tests
• Automated tests passed (QA pipelines)
  • apply
  • upgrade
• Idempotency tested
• Documentation added / updated / doesn't need to be updated
• All conversations in PR resolved
• Solution meets requirements and is done according to design doc
• Usage compliant with license
• Backport tasks created / doesn't need to be backported

[przemyslavic]

Latest images as for today:

Azure
Canonical:UbuntuServer:18.04-LTS:18.04.202109130
RedHat:RHEL:7-LVM:7.9.2021051701
OpenLogic:CentOS:7_9:7.9.2021071900

AWS
ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-20210907
RHEL-7.9_HVM-20210208-x86_64-0-Hourly2-GP2 - currently used
CentOS 7.9.2009 x86_64 - currently used
CentOS 7.9.2009 aarch64 - currently used

[przemyslavic]

Updated defaults, documentation and pipelines.