Roll back Slack failure notification logic for persisting errored TF state

[richgreen-moj]

User Story

As a MP Engineer
I need to roll back the changes made to failure notification logic
So that I am made aware if there are still any errors persisting state to s3

Value / Purpose

We recently made changes to the Slack failure notification logic 918897a so that we could fix an issue where TF state was not persisting to the backend.

Now that this issue is fixed in TF v1.7.5 we should remove this logic...
if: ${{ failure() && !env.STATE_PUSH_SUCCESSFUL }}
so that we know if there are still any failures relating to persisting state to s3.

Useful Contacts

@richgreen-moj @ewastempel

Additional Information

No response

Proposal / Unknowns

Hypothesis If we... [do a thing] Then... [this will happ]

Proposal A proposal that is something testable, don't worry whether it works or not, it's a place for ideas.

Unknowns Potential pitfalls that could cause the story to expand beyond its original scope. Ideally this section will remain blank.

Definition of Done

• Review the logic and make changes as required
• Make sure pipelines are using TF v1.7.5 onwards
• Test changes
• Another team member has reviewed