[WIP] Move OPENTOFU_RUNNER_IMAGE to /etc/defaults

[agrare]

I'm not sure what we will end up calling this properties file, but this shows how we could have a file with all of the images as env vars:

/etc/defaults/manageiq-container-images.properties
OPENTOFU_RUNNER_IMAGE=docker.io/manageiq/opentofu-runner:latest
...

[Fryguy]

Cool I'll link this to my issue

[miq-bot]

Checked commit agrare@8ac7362 with ruby 3.1.5, rubocop 1.56.3, haml-lint 0.51.0, and yamllint
1 file checked, 1 offense detected

app/models/opentofu_worker.rb

• ❗ - Line 94, Col 7 - Layout/HashAlignment - Align the keys and values of a hash literal if they span more than one line.

[miq-bot]

This pull request has been automatically marked as stale because it has not been updated for at least 3 months.

If these changes are still valid, please remove the stale label, make any changes requested by reviewers (if any), and ensure that this issue is being looked at by the assigned/reviewer(s).