Fix/ami authorized keys

[shub-kris]

What does this PR do?

This PR adds ssh_clear_authorized_keys = true in sources.pkr.hcl to clean up the authorized keys so that AMI can be submitted to AWS Marketplace without any error.

Read more about error here.

According to the packer official documentation:

ssh_clear_authorized_keys (bool) - If true, Packer will attempt to remove its temporary key from ~/.ssh/authorized_keys and /root/.ssh/authorized_keys. This is a mostly cosmetic option, since Packer will delete the temporary private key from the host system regardless of whether this is set to true (unless the user has set the -debug flag). Defaults to "false"; currently only works on guests with sed installed.

I tested it by creating a live instance on top of the AMI here built using CI. After launching the AMI, it only contained the key chosen in the AWS "launch instance" wizard, and not the packer temporary keypair.

Fixes # (issue)

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?