[VL] refactor CI cache to use apache stash

[zhouyuan]

Description

Gluten now used actions/cache which has 10GB limitation. Old cache will be evicted and may trigger full build without cache. It's better to switch to use Stash provides a solution for managing large build caches
https://github.com/apache/infrastructure-actions/tree/main/stash

• Save another copy of existing cache to Stash: https://github.com/apache/gluten/blob/main/.github/workflows/velox_backend_cache.yml

• migrate the workflow to use cache from Stash:

• https://github.com/apache/gluten/blob/main/.github/workflows/velox_backend_arm.yml

• https://github.com/apache/gluten/blob/main/.github/workflows/velox_backend_x86.yml

• https://github.com/apache/gluten/blob/main/.github/workflows/velox_backend_enhanced.yml

• clean up the old actions/cache code

Gluten version

None

[Smallfu666]

I'd like to work on this. I'll migrate the Velox ccache restore/save steps to Apache Stash across the listed workflows, preserve the existing cache-key behavior, and validate the workflow YAML before opening a PR.

[Smallfu666]

Following the maintainer's guidance, the work is now split into stages:

• [GLUTEN-12599][VL] Seed Apache Stash CI caches #12602 covers producer-side Stash seeding only and leaves existing CI consumers unchanged.
• After the Stash entries are verified from an apache/main workflow run, I'll open a separate PR to migrate the consumer workflows.
• The legacy actions/cache cleanup will remain a final follow-up after the new path is proven.