Add dummy service accounts to hook-image-puller and continuous-image-puller pods

[samyuh]

This MR adds two separate dummy ServiceAccounts for hook-image-puller and continuous-hook-image-puller.

• The continuous image puller runs constantly to ensure images are always available.
• The hook image puller is temporary, used during tasks like upgrades, and is deleted afterward.

Closes #3545

[consideRatio]

I'm super low on time, but lets try this - do your best to address the review comments, and i'll try get it through to a merge by finishing details this weekend.

Details if you want to try work those as well, from the top of my head would include:

• ensure lint and validate values can trial configure this if new config is introduced
• render and check labels etc align with how other continious/hook resources have labels
  I'm not able to really think properly about this now as i'm taking care of my toddler, sneaking in a review effort quickly from my mobile

[samyuh]

Thanks for the feedback, I will address everything today.

[samyuh]

Tests are failing since https://mybinder.org/ is down.

[consideRatio]

@samyuh great work! I pushed two detail commits.

@manics do you have time for a quick gut-check evaluation? This PR adds two dummy service accounts to be used by the the image-puller pods to please various security checks as discussed in #3545 (comment).

Do we make them enabled by default, or not?

I'm leaning towards enabled by default to reduce the hassle for anyone needing to comply with these benchmarks etc, but I'm not fully confident it has no drawbacks for users in other situations.

[samyuh]

@samyuh great work! I pushed two detail commits.

@manics do you have time for a quick gut-check evaluation? This PR adds two dummy service accounts to be used by the the image-puller pods to please various security checks as discussed in #3545 (comment).

Do we make them enabled by default, or not?

I'm leaning towards enabled by default to reduce the hassle for anyone needing to comply with these benchmarks etc, but I'm not fully confident it has no drawbacks for users in other situations.

Thanks for your effort and your review!