Policy violations should not have a remediate enforcement level. The
Policy SDK currently downgrades the level from remediate to mandatory
for resource policy violations, but isn't currently doing that for stack
policies. A change to the Policy SDK is in-progress to do that.
This change applies the same behavior to the engine. If a resource
policy still has a violation after running remediations and the level is
remediate, "downgrade" the level to mandatory. Similarly, if a stack
policy has a violation with a remediate level, downgrade it to
mandatory.
This avoids a panic when getting a policy violation from a stack policy
and the enforcement level is remediate.
Related: https://github.com/pulumi/pulumi-policy/pull/339
Fixes https://github.com/pulumi/pulumi-policy/issues/332