ci: fix drift detection by setting --detailed-exitcode if running as cron

From terraform plan --help
>  -detailed-exitcode  Return detailed exit codes when the command exits. This
>                      will change the meaning of exit codes to:
>                      0 - Succeeded, diff is empty (no changes)
>                      1 - Errored
>                      2 - Succeeded, there is a diff

.drone.yml

@@ -34,7 +34,7 @@ steps:
 - name: terraform plan
   image: hashicorp/terraform:1.1.8
   commands:
-    - terraform plan -var-file ci.tfvars -out .tfplan
+    - terraform plan $([[ $${DRONE_BUILD_EVENT} = cron ]] && echo "--detailed-exit-code") -var-file ci.tfvars -out .tfplan
   environment:
     AWS_ACCESS_KEY_ID:
       from_secret: terraform-aws-key-id
@@ -56,18 +56,6 @@ steps:
   image: hashicorp/terraform:1.1.8
   commands:
     - terraform apply .tfplan
-  environment:
-    AWS_ACCESS_KEY_ID:
-      from_secret: terraform-aws-key-id
-    AWS_SECRET_ACCESS_KEY:
-      from_secret: terraform-aws-secret-access-key
-    KUBE_TOKEN:
-      from_secret: lawndale-k8s-ci-token
-    TF_VAR_lawndale_dns_key_secret:
-      from_secret: lawndale-dns-key-secret
-    TF_VAR_lawndale_dns_key_algorithm:
-      from_secret: lawndale-dns-key-algorithm
-
 ---
 kind: pipeline
 type: kubernetes
@@ -92,6 +80,6 @@ steps:
 
 ---
 kind: signature
-hmac: 1a1e96092143802284d04077f335273f767aeeb7122438b1538e170da4d35da5
+hmac: 3fc2a7491b8914bbb9225195340bc9cf7ead5c3e7e25a847923c6ad78be405a2
 
 ...