[CI] Refactor to speedup image building and CI Installation (#6708)

### What this PR does / why we need it?
1. Refactor  image workflow using cache-from to speedup builds

![build](https://github.com/user-attachments/assets/02135c12-0069-44f8-a3ec-5c2b4282448a)

Simultaneously refactored all Dockerfiles by placing layers that rarely
change before those that change frequently, improving build cache hit
rate.

2. Refactor E2E test using vllm-ascend container images, to skip C
compile while no C code are changed

![e2e](https://github.com/user-attachments/assets/49f5b166-0df3-41e1-8f71-b3bbbed17cfd)

In this case, the job will only replace the source code of vllm-ascend
and install `requirements-dev.txt`, saving about 10min before tests

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.15.0
- vLLM main:
9562912cea

Signed-off-by: wjunLu <wjunlu217@gmail.com>

.github/workflows/schedule_image_build_and_push.yaml

@@ -12,12 +12,15 @@
 name: Image Build and Push
 on:
   schedule:
-    # UTC+8: 8am, 12pm, 16pm, 22pm
-    - cron: '0 0,4,8,14 * * *'
+    # UTC+8: 8am, 10am, 12pm, 14pm, 16pm, 18pm, 22pm
+    - cron: '0 0,2,4,6,8,10,14 * * *'
   push:
+    branches:
+      # Build release branch images proactively so cache is warm when the tag is pushed
+      - 'releases/*'
     tags:
       - 'v*'
-  pull_request: 
+  pull_request:
     branches:
       - 'main'
     types: [ labeled, synchronize ]