release.yaml: share duplicated steps with YAML anchors

patch/minor/major create steps were three byte-identical copies apart
from a stray echo and the release type in the commit message and PR
title. The type is already recorded in the commit body via {{config}},
and the Temporal release workflow already titles these PRs
"(internal) release: build vX", so the copies collapse into one anchored
list.

The public-registry sg ops steps, chart:version, chart:appVersion and
helm-docs steps were also repeated between promoteToPublic.create and
promoteToPublic.finalize; they are now defined once and aliased.

Rendered steps for every operation (sg release steps) are unchanged
except for the intended commit message / PR title / step-name edits.

615 -> 354 lines.

Amp-Thread-ID: https://ampcode.com/threads/T-01a0f395-3034-73c8-90dc-e665c3d9477f
Co-authored-by: Amp <amp@ampcode.com>

Author: marcleblanc2