[GH] (texera/main): Workflow run "Create and upload release candidate artifacts" is working again!

[GitBox <gi...@apache.org>]

The GitHub Actions job "Create and upload release candidate artifacts" on texera.git/main has succeeded.
Run started by GitHub user bobbai00 (triggered by bobbai00).

Head commit for run:
7048ce340a2557ff3810206c8583c3e775972746 / Jiadong Bai <43...@users.noreply.github.com>
chore: update release workflow to comply with Apache release practice (#4128)

### What changes were proposed in this PR?

Update release candidate workflow and vote email template based on
Apache mentor feedback:

1. **KEYS URL**: Changed to
`https://downloads.apache.org/incubator/texera/KEYS` (official location,
auto-synced from release)
2. **Tarball naming**: Removed 'rc' suffix from filename
(`apache-texera-X.Y.Z-incubating-src.tar.gz`). RC number remains in
directory name.
3. **Vote email**: Simplified verification instructions (removed wget
commands), added convenience binaries section

### Any related issues, documentation, discussions?

Fixes #4127

### How was this PR tested?

Template and workflow changes reviewed manually.

### Was this PR authored or co-authored using generative AI tooling?

Co-authered with Claude Code (Claude Opus 4.5)

---------

Co-authored-by: Claude Opus 4.5 <no...@anthropic.com>

Report URL: https://github.com/apache/texera/actions/runs/21875841639

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