Always provision source controller IRSA role with the cluster and allow for pulls through pull through cache

[wcarlsen]

Describe your changes

Currently source controller IRSA role is a shared role from shared-prod account, but since we implement allowed pulls if it is form an org account, we no longer need the shared account approach. So we let the clusters bring its own. We also solve a bug with the shared-prod IRSA role missing permissions to pull images from the pull through cache. Lastly this hopefully removes flaky diffs and random failures on fluxcd_bootstrap_git resource as described here https://dfds.slack.com/archives/CQD754GGL/p1782994535687589.

Issue ticket number and link

Checklist before requesting a review

• I have tested changes in my sandbox
• I have added the needed changes in the test/integration folder to apply my changes in QA. Read the guide on adding environment variables in QA
• I have rebased the code to master (or merged in the latest from master)

Is it a new release?

• Apply a release tag release:(major|minor|patch), following semantic versioning in this guide or norelease if there is no changes to the Terraform code

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[wcarlsen]

I guess that triggered a bug in the provider 🙈

[wcarlsen]

I guess that triggered a bug in the provider 🙈

So on first run this fails, with an inconsistent plan from the provider, but it disappears on second run.