SSM Agent Installation fails if already installed

[pjaudiomv]

What happened:
When custom AMI already has SSM agent the packer build fails

What you expected to happen:
skip the package gracefully

How to reproduce it (as minimally and precisely as possible):
Use CIS Amazon Linux 2 Benchmark - STIG as base AMI
Returns Error:

2023-10-31T14:04:19-04:00:     amazon-ebs: Examining /var/tmp/yum-root-DVDoG9/amazon-ssm-agent.rpm: amazon-ssm-agent-3.2.1705.0-1.x86_64
2023-10-31T14:04:19-04:00:     amazon-ebs: /var/tmp/yum-root-DVDoG9/amazon-ssm-agent.rpm: does not update installed package.
2023-10-31T14:04:19-04:00:     amazon-ebs: Error: Nothing to do

Anything else we need to know?:

This worked until v20230816 release.

If I just run sudo yum install -y amazon-ssm-agent in install-worker.sh the build runs fine. It doesn't not when specifying an RPM package sudo yum install -y https://s3.${BINARY_BUCKET_REGION}.${S3_DOMAIN}/amazon-ssm-${BINARY_BUCKET_REGION}/${SSM_AGENT_VERSION}/linux_${ARCH}/amazon-ssm-agent.rpm

This relates to #685

Maybe just adding a check for agent or/and agent version would suffice.

Environment:

• AWS Region: us-gov-west-1
• Instance Type(s): m5.large
• EKS Platform version (use aws eks describe-cluster --name <name> --query cluster.platformVersion):
• Kubernetes version (use aws eks describe-cluster --name <name> --query cluster.version): 1.27.6
• AMI Version: AL2 Stig AMI
• Kernel (e.g. uname -a):
• Release information (run cat /etc/eks/release on a node):

[cartermckinnon]

Feel free to open a PR, you can do a check like this to only install when necessary:

amazon-eks-ami/scripts/install-worker.sh

Lines 96 to 97 in 7e6c213

	# Remove the ec2-net-utils package, if it's installed. This package interferes with the route setup on the instance.
	if yum list installed | grep ec2-net-utils; then sudo yum remove ec2-net-utils -y -q; fi

[pjaudiomv]

Feel free to open a PR, you can do a check like this to only install when necessary:

amazon-eks-ami/scripts/install-worker.sh

Lines 96 to 97 in 7e6c213

	# Remove the ec2-net-utils package, if it's installed. This package interferes with the route setup on the instance.
	if yum list installed | grep ec2-net-utils; then sudo yum remove ec2-net-utils -y -q; fi

Thanks just did here #1501

[pjaudiomv]

Fixed with merging of #1501