Simplify codebase: modernize loops, split templates, improve CI (#14891)

* Simplify codebase: remove dead venv files, consolidate loops, modernize patterns

- Delete 8 empty venv.yml files that were remnants of pyproject.toml migration
- Remove corresponding import_tasks references from cloud provider main.yml files
- Consolidate server.yml async polling from 4 copy-paste blocks to 1 loop
- Wrap sequential VPN service imports in a block with single when condition
- Replace deprecated with_indexed_items with modern loop/loop_control syntax

These changes reduce maintenance burden by:
- Eliminating 8 files that served no purpose
- Reducing server.yml by ~20 lines while improving readability
- Removing Ansible deprecation warnings for with_indexed_items
- Making the parallel/sequential execution paths easier to maintain

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* Fix template variable and undefined job variable bugs

- Fix client.conf.j2 to use `item` instead of `item.1` to match modern
  loop syntax (loop with index_var instead of with_indexed_items)
- Fix server.yml _vpn_jobs to use `| default({})` for job variables
  that may be undefined when running with tags (e.g., IPsec-only)
- Update test_template_rendering.py to pass item as string instead of
  tuple, matching the new loop behavior

Fixes CI failures from PR #14891 that were correctly identified by the
Claude Code bot review.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

---------

Co-authored-by: Claude <[email protected]>

Author: dguido

roles/cloud-azure/tasks/main.yml

@@ -1,7 +1,4 @@
 ---
-- name: Build python virtual environment
-  import_tasks: venv.yml
-
 - name: Include prompts
   import_tasks: prompts.yml
 

roles/cloud-azure/tasks/venv.yml

@@ -1,7 +1,4 @@
 ---
-- name: Build python virtual environment
-  import_tasks: venv.yml
-
 - name: Include prompts
   import_tasks: prompts.yml
 

roles/cloud-cloudstack/tasks/main.yml

@@ -1,7 +1,4 @@
 ---
-- name: Build python virtual environment
-  import_tasks: venv.yml
-
 - name: Include prompts
   import_tasks: prompts.yml
 

roles/cloud-cloudstack/tasks/venv.yml

@@ -1,7 +1,4 @@
 ---
-- name: Build python virtual environment
-  import_tasks: venv.yml
-
 - name: Include prompts
   import_tasks: prompts.yml
 

roles/cloud-ec2/tasks/main.yml

@@ -1,7 +1,4 @@
 ---
-- name: Build python virtual environment
-  import_tasks: venv.yml
-
 - name: Include prompts
   import_tasks: prompts.yml