Add tflint to pipelines (#2220)

* Fix terraform_deprecated_index

https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.5.0/docs/rules/terraform_deprecated_index.md

* Fix terraform_deprecated_interpolation

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.5.0/docs/rules/terraform_deprecated_interpolation.md

* Fix more indexing

* Remove unused variable

* Enable TFLint for modules

* Add tflint config file

* Fix chdir

* Lint modules

* TFLint fixes

* TFLint

* Fixes binauthz README

* Fixes DNS response policy tests. Restores MIG outputs.

* Fixes other DNS response policy tests.

* Update tests for fast 2-e

* Moar fixed tests

---------

Co-authored-by: Simone Ruffilli <sruffilli@google.com>

modules/__experimental_deprecated/cloud-identity-group-factory/main.tf

@@ -1,5 +1,5 @@
 /**
- * Copyright 2022 Google LLC
+ * Copyright 2024 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,7 @@
 
 locals {
   groups = {
-    for f in fileset("${var.data_dir}", "**/*.yaml") :
+    for f in fileset(var.data_dir, "**/*.yaml") :
     trimsuffix(f, ".yaml") => yamldecode(file("${var.data_dir}/${f}"))
   }
 }