fix: bug in tflint and s2s test

[ChrisSidebotham]

Description

Fixing current bugs in tflint & S2S Example where customer VPN had incorrect sku of Public IP

Type of Change

• [ ] Non-module change (e.g. CI/CD, documentation, etc.)
• [x] Azure Verified Module updates:
  • [x] Bugfix containing backwards compatible bug fixes, and I have NOT bumped the MAJOR or MINOR version in locals.version.tf.json:
  • [ ] Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
  • [x] The bug was found by the module author, and no one has opened an issue to report it yet.
  • [ ] Feature update backwards compatible feature updates, and I have bumped the MINOR version in locals.version.tf.json.
  • [ ] Breaking changes and I have bumped the MAJOR version in locals.version.tf.json.
  • [ ] Update to documentation

Checklist

• [x] I'm sure there are no other open Pull Requests for the same update/change
• [x] My corresponding pipelines / checks run clean and green without any errors or warnings
• [x] I did run all pre-commit checks