[CI] Avoid lint and ut for PR push (#5762)

1. Don't run lint and ut again once the PR is merged to save CI resource
2. Update codecov every 4 hour
3. rename `model_downloader` to suitable name
4. update schedule job to better time.

- vLLM version: v0.13.0
- vLLM main:
2f4e6548ef

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

.github/workflows/labled_test_310.yaml

@@ -18,9 +18,6 @@
 name: 310p Labeled Test
 
 on:
-  push:
-    tags:
-      - 'v*'
   pull_request:
     types: [ labeled ]