[ci] Add branch-4.1 thirdparty prebuilt and Docker release

[hello-stephen]

Summary

Add a dedicated GitHub Actions workflow for Doris branch-4.1, with its own automation-4.1 release, Linux x86_64 and macOS arm64 prebuilt archives, and Docker Hub tags:

• apache/doris:build-env-ldb-toolchain-4.1-latest
• apache/doris:build-env-ldb-toolchain-4.1-no-avx2-latest

The workflow tracks thirdparty/ changes for full releases and docker/compilation/Dockerfile changes for image-only updates. It also supports manual full and Docker-only runs. Both the build checkout and Dockerfile use the Doris SHA chosen by prerelease; the image step verifies the Linux archive's thirdparty commit marker before pushing. Scheduled retries are bounded and preserve Docker-only scope.

Validation

• actionlint .github/workflows/build-4.1.yml
• git diff --check
• Ran the Dockerfile transformation against Doris branch-4.1 SHA 30535aa6f037b7d7d69a0d8114e6e69c147027c9; both normal and no-avx2 Dockerfiles generated with the automation-4.1 archive.
• Exercised the prerelease decision script with first release, unrelated change, thirdparty change, Dockerfile-only change, manual Docker-only run, and bounded failure retries.

The workflow has not been run on GitHub Actions yet. The release assets and Docker tags will be produced after this workflow lands on the default branch and its first scheduled or manual run completes.