unreliable test: checkNoNewAccess should handle Terraform Plan correctly:

## Test Details

- Name of test: checkNoNewAccess should handle Terraform Plan correctly:
- OS of failure: Mac
- VSCode version of failure (minimum/insider/stable): minimum
- Link to failing run: https://github.com/aws/aws-toolkit-vscode/actions/runs/13206848909/job/36871882448
- Link to failing test: https://github.com/aws/aws-toolkit-vscode/blob/67f053c19b7d8703c1dc4989a853bc4cc44e3919/packages/core/src/test/awsService/accessanalyzer/iamPolicyChecks.test.ts#L346-L376

## Log of Test Failure
```
checkNoNewAccess should handle Terraform Plan correctly:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:

(0, assert_1.default)(executeCustomPolicyChecksCommandStub.called)

+ expected - actual

-false
+true
```

## Additional Information

Start with packages/core/src/test/awsService/accessanalyzer/iamPolicyChecks.test.ts at the linked lines and run the failing checkNoNewAccess test or workflow. Investigate why executeCustomPolicyChecksCommandStub.called is false during the Terraform Plan case. Done means the test reliably exercises the expected command and passes on the relevant workflow.

Written by the indexing model from the issue text.