ci: remove AWS S3 upload from release workflow (#1103)

### Description of the change

Remove the AWS S3 upload steps from the release workflow. Charts are now published only to Cloudflare R2 (plus the OCI registry on Docker Hub).

Removed steps:
- `aws credential configure` (`aws-actions/configure-aws-credentials`)
- `Copy files to S3 and clear cache`

The `awscli` install step is kept, since the Cloudflare R2 sync still uses `aws s3 sync` with a custom endpoint.

### Benefits

- One less publishing target to keep in sync, removing duplicated chart uploads.
- The `AWS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`, `AWS_REGION` and `AWS_S3_BUCKET` secrets are no longer needed.

### Possible drawbacks

Anything still pointing at the S3 bucket directly will no longer receive new chart releases; the Cloudflare R2 bucket behind `https://dl.gitea.com/charts` must be the only source of truth.

---------

Co-authored-by: bircni <bircni@icloud.com>
Reviewed-on: https://gitea.com/gitea/helm-gitea/pulls/1103
Reviewed-by: bircni <bircni@icloud.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

.gitea/workflows/release-version.yml

@@ -85,17 +85,6 @@ jobs:
           helm push gitea/gitea-${GITHUB_REF#refs/tags/v}.tgz oci://registry-1.docker.io/giteacharts
           helm registry logout registry-1.docker.io
 
-      - name: aws credential configure
-        uses: https://github.com/aws-actions/configure-aws-credentials@v6
-        with:
-          aws-access-key-id: ${{ secrets.AWS_KEY_ID }}
-          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
-          aws-region: ${{ secrets.AWS_REGION }}
-
-      - name: Copy files to S3 and clear cache
-        run: |
-          aws s3 sync gitea/ s3://${{ secrets.AWS_S3_BUCKET}}/charts/
-
       - name: Copy files to Cloudflare R2
         env:
           AWS_ACCESS_KEY_ID: ${{ secrets.CLOUDFLARE_R2_ACCESS_KEY_ID }}