Fix etcd-network-tuning.sh location for Flatcar

[kopiczko]

What steps did you take and what happened:

After merging #901 flatcar build fails because of read-only /usr/local/bin:

    qemu: TASK [node : Copy etcd network tuning script] **********************************
    qemu: fatal: [default]: FAILED! => {"changed": false, "checksum": "9b8498c353396b5550fde1af334e0f4030c7b7bd", "msg": "Destination /usr/local/bin not writable"}

What did you expect to happen:

Build passing.

Anything else you would like to add:

N/A

Environment:

Project (Image Builder for Cluster API, kube-deploy/imagebuilder, konfigadm):

Additional info for Image Builder for Cluster API related issues:

• OS (e.g. from /etc/os-release, or cmd /c ver): macOS 12.4
• Packer Version: 1.8.0
• Packer Provider:
• Ansible Version: 2.12.5
• Cluster-api version (if using):
• Kubernetes version: (use kubectl version):

/kind bug
[One or more /area label. See https://github.com/kubernetes-sigs/cluster-api/labels?q=area for the list of labels]

CC @invidian

[invidian]

I think /opt/bin could be used as an alternative for Flatcar.

[invidian]

FYI opened #923 as an alternative to #907, which addresses only this issue, so should be easier to merge. It also uses /opt/bin only for Flatcar.