Stop using the (deprecated) commit-warehouse

The warehouse is no longer necessary thanks to https://github.com/docker-library/bashbrew/pull/4 🥳

(This is essentially a revert of 85113ccb29)

.template-helpers/git-prefetch.sh

@@ -1,54 +0,0 @@
-#!/usr/bin/env bash
-set -Eeuo pipefail
-
-repo="${1:-}"
-if [ -z "$repo" ]; then
-	echo >&2 "usage: $0 repo"
-	echo >&2 "   ie: $0 hylang"
-	exit 1
-fi
-
-# if we haven't set BASHBREW_LIBRARY explicitly (like Jenkins does, for example), don't trust the local library
-if [ -z "${BASHBREW_LIBRARY:-}" ]; then
-	repo="https://github.com/docker-library/official-images/raw/master/library/$repo"
-fi
-
-: "${BASHBREW_CACHE:=$HOME/.cache/bashbrew}"
-export BASHBREW_CACHE
-
-# see "generate-dockerfile-links-partial.tmpl" for where our arch-choosing complexity comes from
-templateHeader='{{- $archSpecific := getenv "ARCH_SPECIFIC_DOCS" -}}'
-templateArchVar='{{- $arch := $archSpecific | ternary arch ($e.HasArchitecture arch | ternary arch ($e.Architectures | first)) -}}'
-
-tags="$(bashbrew list --uniq "$repo" | cut -d: -f2-)"
-tags=( $tags )
-toFetch=()
-for tag in "${tags[@]}"; do
-	if ! bashbrew cat --format '
-		'"$templateHeader"'
-		{{- $e := $.TagEntry -}}
-		'"$templateArchVar"'
-		{{- if $e.HasArchitecture $arch -}}
-			{{- $froms := $.ArchDockerFroms $arch $e -}}
-		{{- end -}}
-	' "$repo:$tag" &> /dev/null; then
-		toFetch+=( "$repo:$tag" )
-	fi
-done
-
-if [ "${#toFetch[@]}" -eq 0 ]; then
-	exit 0
-fi
-
-bashbrewFetchTemplate='
-	'"$templateHeader"'
-	{{- range $i, $e := ($archSpecific | ternary (archFilter arch $.Entries) $.Entries) -}}
-		'"$templateArchVar"'
-		{{- join "/" "refs/tags" $arch $.RepoName ($e.Tags | first) -}}
-		{{- ":" -}}
-		{{- "\n" -}}
-	{{- end -}}
-'
-
-bashbrew cat --format "$bashbrewFetchTemplate" "$repo" \
-	| xargs --no-run-if-empty git -C "$BASHBREW_CACHE/git" fetch --quiet --no-tags https://github.com/docker-library/commit-warehouse.git

update.sh

@@ -111,9 +111,6 @@ for image in "${images[@]}"; do
 			deprecated+=$'\n\n'
 		fi
 
-		echo '  GIT PREFETCH => "'"$repo"'"'
-		"$helperDir/git-prefetch.sh" "$repo"
-
 		if ! partial="$("$helperDir/generate-dockerfile-links-partial.sh" "$repo")"; then
 			{
 				echo