fix(P60): ALB target group name_prefix — avoid orphaned resource conflicts

The ALB lifecycle test was failing with "ELBv2 Target Group (acdl-ci-alb)
already exists" because a prior failed run left an orphaned target group
in AWS. The deterministic state key means terraform reuses the same state,
but create_before_destroy tries to create a new target group with the same
name before destroying the old one → conflict.

Fix: use name_prefix instead of name for the target group. AWS auto-generates
a unique name (e.g. acdl-ci-alb-2026072812001234567), so create_before_destroy
can create the new target group without conflicting with the orphaned one.
The old orphaned target group is eventually garbage-collected by AWS (or
cleaned up by a future run's destroy step).

This is the standard terraform pattern for create_before_destroy resources
with name uniqueness constraints.

---ci---
project: acdl
phase: P60
milestone: v1.11
status: execute
---/ci---

modules/l1/alb/terraform/main.tf

@@ -6,7 +6,7 @@ resource "aws_lb" "this" {
 }
 
 resource "aws_lb_target_group" "this" {
-  name        = var.name
+  name_prefix = "${var.name}-"
   port        = var.port
   protocol    = var.protocol
   vpc_id      = var.vpc_id