chore: update service_account_id output variable

Author: q2w

modules/instance_template/main.tf

@@ -18,6 +18,12 @@
 # Locals
 #########
 
+data "google_service_account" "existing_sa" {
+  count      = local.create_service_account == false ? 1 : 0
+  account_id = element(split("@", google_cloud_run_v2_service.main.template[0].service_account), 0)
+  project    = element(split("@", element(split(".", google_cloud_run_v2_service.main.template[0].service_account), 0)), 1)
+}
+
 locals {
   source_image         = var.source_image != "" ? var.source_image : "rocky-linux-9-optimized-gcp-v20240111"
   source_image_family  = var.source_image_family != "" ? var.source_image_family : "rocky-linux-9-optimized-gcp"
@@ -80,7 +86,11 @@ locals {
     id     = google_service_account.sa[0].account_id,
     email  = google_service_account.sa[0].email,
     member = google_service_account.sa[0].member
-  } : {}
+    } : {
+    id     = data.google_service_account.existing_sa[0].account_id,
+    email  = data.google_service_account.existing_sa[0].email,
+    member = data.google_service_account.existing_sa[0].member
+  }
 }
 
 # Service account