[Release] Consolidate the HF CLI skill sync into the release workflow (#4765)
* [Release] Drop duplicate HF CLI skill sync job
Every release opened two PRs on huggingface/skills: one from this job and
one from sync-hf-cli-skill.yml, which the release tag push also triggers.
Only the standalone workflow bumps the plugin version and regenerates the
skills repo artifacts, so its PR is the one that passes validate.
* [Release] Keep the skill sync in the release workflow instead
Reverses the previous commit's direction: rather than deleting the job and
relying on the tag-triggered workflow, port the working implementation (uv,
plugin version bump, publish.sh, SKILL.md-scoped diff) into the release job
and delete sync-hf-cli-skill.yml. One sync, inside the workflow that already
reports to the release Slack thread and the final status check.
The PR body now points at the release tag rather than github.sha, which on a
workflow_dispatch run is main's HEAD, not the commit that was synced.