Keep run logs around even after a stack is deleted

We use a merge-before-apply workflow and have found that the easiest way to remove a Terraform directory is to open 2 separate PRs:

1. First PR removes all the Terraform resource definitions but not the Terraform provider/state config

2. Second PR removes the remaining resources, and needs the Spacelift stack deleted before it can be merged (I think - I’m pretty sure disabling stacks causes Spacelift to send admin errors and won’t make the spacelift/proposed PR check ignore the stack)

It would be nice if deleting a stack did not delete the related run logs until they expire if you visit a run’s logs URL directly. This would pair nicely with the feature request to allow us to store logs longer and would make it easier to remove Terraform directories.

One more thing re: the second PR - it seems push policies don’t get access to the stack’s disabled property, so we can’t choose to ignore runs for a disabled stack. Instead I get an admin notification that the run couldn’t start and an PR check with an error appears on the triggering commit.