archlinux: Use hostnamectl to set the transient hostname

[klausenbusk]

Proposed Commit Message

archlinux: Use hostnamectl to set the transient hostname

hostname (inetutils) isn't installed per default on arch, so switch
to hostnamectl which is installed per default (systemd).

Test Steps

This has been tested manually with the Arch Linux cloud-init package (arch.py patched with the changes in this commit) and inetutils forcefully removed (pacman -Rsddn inetutils).

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[klausenbusk]

The CLA stuff is part of: #796

[TheRealFalcon]

Your commit message lists the reason for making the change, but can you add a comment to the method to explain why you're overriding the default behavior? Also, can you add similar logging and try/except behavior that the base method has?

[klausenbusk]

Fixed

[TheRealFalcon]

I suggested one more change inline. Should be good to go after that. I'll wait for your other PR to merge given that the CLA change is in that one.

[TheRealFalcon]

Thanks!

[TheRealFalcon]

Hey @klausenbusk , the only thing this PR is waiting on is the CLA signers file, which is added in #796 . If you need to take your time on #796 , feel free to move that commit over to this PR and I can land this one as soon as possible. If you'd rather just wait until the other PR is finished, that is fine as well.

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging mitechie, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag mitechie to reopen it.)

[TheRealFalcon]

@klausenbusk , since this PR was close to getting auto-closed, and since you've already signed the CLA, I took the liberty of moving your addition to the github CLA signers file over to this PR and merging it. Thanks for the contribution!