Adding terraform fmt to the Terraform template

What does this MR do?

Adds a new job under the validate stage and performs a terraform fmt in the Terraform template.

Related issues

• #339935 (closed)

Check-list

Pre-merge

Consider the effect of the changes in this merge request on the following:

• Different pipeline types
• Non-canonical projects:
  • gitlab-foss
  • security
  • dev
  • personal forks
• Pipeline performance

If new jobs are added:

• Change-related rules (e.g. frontend/backend/database file changes): _____
• Frequency they are running (MRs, main branch, nightly, bi-hourly): _____
• Add a duration chart to https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations if there are new jobs added to merge request pipelines

This will help keep track of expected cost increases to the GitLab project average pipeline cost per merge request RPI

Post-merge

• Consider communicating these changes to the broader team following the communication guideline for pipeline changes