Remove reliance on remote backend

[dms1981]

Relevant Issue: ministryofjustice/modernisation-platform#2647

Because the infrastructure created by terratest code is transient and to minimise the overhead of managing additional terraform state, the terratest code is being shifted to use local backend that doesn't persist the state between runs. The change makes the use of terraform workspaces irrelevant.

• Update go-terratest workflow to remove the code explicitly selecting a workspace
• Update README.md in the test folder to remove references to terraform workspaces
• Update go code to remove set workspace command and merge Init + Apply back into one statement
• Remove backend.tf from unit-test code
• Update providers.tf to remove references to terraform.workspace
  Additionally some minor changes for consistency and neatness.

[github-actions]

TFSEC Scan Success

Show Output

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TFSEC will check the following folders:
.

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Running TFSEC in .
Excluding the following checks: AWS089, AWS099, AWS009, AWS097, AWS018
  timings
  ──────────────────────────────────────────
  disk i/o             111.903µs
  parsing              4.838213ms
  adaptation           638.615µs
  checks               21.599312ms
  total                27.188043ms

  counts
  ──────────────────────────────────────────
  modules downloaded   0
  modules processed    1
  blocks processed     61
  files read           4

  results
  ──────────────────────────────────────────
  passed               8
  ignored              34
  critical             0
  high                 0
  medium               0
  low                  0


No problems detected!

tfsec_exitcode=0

Checkov Scan Success

Show Output

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Checkov will check the following folders:
.

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Running Checkov in .
Excluding the following checks: CKV_GIT_1
2022-11-23 16:46:04,146 [MainThread  ] [WARNI]  Failed to download module github.com/ministryofjustice/modernisation-platform-terraform-ecs?ref=e57c01f26ddc488fe6c83bfdc2817510f44f3b19:None (for external modules, the --download-external-modules flag is required)
Process ForkProcess-11:
Traceback (most recent call last):
  File "/usr/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
    self.run()
  File "/usr/lib/python3.7/multiprocessing/process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.7/dist-packages/checkov/common/parallelizer/parallel_runner.py", line 37, in func_wrapper
    result = original_func(item)
  File "/usr/local/lib/python3.7/dist-packages/checkov/common/runners/runner_registry.py", line 89, in _parallel_run
    collect_skip_comments=collect_skip_comments,
  File "/usr/local/lib/python3.7/dist-packages/checkov/github/runner.py", line 34, in run
    self.prepare_data()
  File "/usr/local/lib/python3.7/dist-packages/checkov/github/runner.py", line 43, in prepare_data
    self.github.persist_all_confs()
  File "/usr/local/lib/python3.7/dist-packages/checkov/github/dal.py", line 137, in persist_all_confs
    self.persist_branch_protection_rules()
  File "/usr/local/lib/python3.7/dist-packages/checkov/github/dal.py", line 69, in persist_branch_protection_rules
    BaseVCSDAL.persist(path=self.github_branch_protection_rules_file_path, conf=data)
  File "/usr/local/lib/python3.7/dist-packages/checkov/common/vcs/base_vcs_dal.py", line 113, in persist
    BaseVCSDAL.ensure_dir(path)
  File "/usr/local/lib/python3.7/dist-packages/checkov/common/vcs/base_vcs_dal.py", line 123, in ensure_dir
    os.makedirs(directory_path)
  File "/usr/lib/python3.7/os.py", line 221, in makedirs
    mkdir(name, mode)
FileNotFoundError: [Errno 2] No such file or directory: ''
terraform scan results:

Passed checks: 38, Failed checks: 0, Skipped checks: 10

github_actions scan results:

Passed checks: 123, Failed checks: 0, Skipped checks: 0


checkov_exitcode=0

CTFLint Scan Success

Show Output

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Setting default tflint config...
Running tflint --init...
Installing `terraform` plugin...
Installed `terraform` (source: github.com/terraform-linters/tflint-ruleset-terraform, version: 0.2.1)
tflint will check the following folders:
.

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Running tflint in .
tflint_exitcode=0

[julialawrence]

LGTM