[NRL-1386] Fix TF bug in infra with firehose__processor

Author: mattdean3-nhs

terraform/infrastructure/locals.tf

@@ -33,8 +33,8 @@ locals {
   reporting_bucket_arn = data.aws_s3_bucket.source-data-bucket.arn
   reporting_kms_arn    = data.aws_kms_key.glue.arn
   firehose_lambda_subscriptions = var.use_shared_resources ? [
-    module.firehose__processor.firehose_subscription,
-    module.firehose__processor.firehose_reporting_subscription
+    module.firehose__processor[0].firehose_subscription,
+    module.firehose__processor[0].firehose_reporting_subscription
   ] : []
   splunk_environment = local.is_sandbox_env ? "${var.account_name}sandbox" : var.account_name
   splunk_index       = "aws_recordlocator_${local.splunk_environment}"