Edits in backend.rb to include some common error handling

Description

Initial edits to include some error handling, requires discussion with the SAP MCDevOps team about future development

Issues Resolved

When checking for control exceptions, our team has noticed a high number of controls which are failing due to various errors. The purpose of this PR is to add in error handling for the errors included, namely Aws::Errors::NoSuchEndpointError and Errors::InvalidClientTokenId. Additionally, this PR should be held off on being merged, as discussion is required between the Chef team and the SAP MCDevSecOps team as to how best proceed with the handling of errors.

Check List

Please fill box or appropriate ([x]) or mark N/A.

[ ] New functionality includes integration tests/controls
[ ] New Terraform resources
[ ] Documentation provided or updated for resources
[ ] All Integration Tests pass
[ ] All Unit Tests pass
[x] rake lint passes
[x] All commits have been signed-off for the Developer Certificate of Origin. See https://github.com/chef/chef/blob/master/CONTRIBUTING.md#developer-certification-of-origin-dco

inspec / inspec-aws