[BUG] Inspector enabler lambda exits prematurely

### Describe the bug

Inspector enabler lambda _sra-inspector-org_ exits prematurely when doing boto3 call to get_member (https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/inspector2/client/get_member.html#).
The result is that mgmt account and all the other member accounts does not get inspector enabled.
Only the delegated admin (audit account) does get inspector enabled.

### To Reproduce

Steps to reproduce the behavior:

1. Deploy cloudformation solution SRA with inspector like so:
aws cloudformation deploy --template-file aws_sra_examples/easy_setup/templates/sra-easy-setup.yaml --stack-name sra-easy-setup --s3-bucket --capabilities CAPABILITY_NAMED_IAM --parameter-overrides pDeployGuardDutySolution=Yes pDeployConfigManagementSolution=Yes pDeploySecurityHubSolution=Yes pSRAAlarmEmail= **pDeployInspectorSolution=Yes**

### Expected behavior

Stack succeeds and lambda does not produce any error in the lambda log.

### Current behavior

Stack succeeds and lambda produce error in the lambda log.

### Screenshots

If applicable, add screenshots to help explain your problem.

### Deployment Environment (please complete the following information)

- Deployment Framework [e.g. Customizations for Control Tower and CloudFormation StackSets]:
CloudFormation StackSets
- Deployment Framework Version [e.g. 1.0, 2.0]:
main branch

### Additional context

Stacktrace from lambda log:

{
"timestamp": "2025-09-17 10:32:30,915",
"level": "ERROR",
"location": "sra.lambda_handler:586",
"RequestType": "ContainerInit",
"message": "Unexpected!",
"exception": "Traceback (most recent call last):\n File \"/var/task/app.py\", line 584, in lambda_handler\n orchestrator(event, context)\n File \"/var/task/app.py\", line 562, in orchestrator\n process_event_sns(event)\n File \"/var/task/app.py\", line 535, in process_event_sns\n setup_inspector_in_region(\n File \"/var/task/app.py\", line 417, in setup_inspector_in_region\n inspector.associate_inspector_member_accounts(configuration_role_name, delegated_admin_account, accounts, region)\n File \"/var/task/inspector.py\", line 557, in associate_inspector_member_accounts\n if lookup_associated_accounts(inspector_delegated_admin_region_client, account[\"AccountId\"]) is True:\n **File \"/var/task/inspector.py\", line 131, in lookup_associated_accounts\n response = inspector2_client.get_member(accountId=account_id)\n** File \"/opt/python/botocore/client.py\", line 602, in _api_call\n return self._make_api_call(operation_name, kwargs)\n File \"/opt/python/botocore/context.py\", line 123, in wrapper\n return func(*args, **kwargs)\n File \"/opt/python/botocore/client.py\", line 1078, in _make_api_call\n raise error_class(parsed_response, operation_name)\nbotocore.errorfactory.InternalServerException: An error occurred (InternalServerException) when calling the GetMember operation (reached max retries: 4): Failure to process account: 573673592501, errorMessage: The request is rejected because the given account ID is not an associated member of the current account."
}

Start in inspector.py at lookup_associated_accounts and follow its callers into associate_inspector_member_accounts and app.py's setup_inspector_in_region. Reproduce the CloudFormation StackSets deployment with pDeployInspectorSolution=Yes, then inspect the Lambda logs around the Inspector get_member call. Done means the stack completes without this error and Inspector is enabled for the management and member accounts.

Written by the indexing model from the issue text.