Improve docker build (#24692)

* better caching, reduce context size, etc

.github/actions-scripts/merge-early-access.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+# [start-readme]
+#
+# This script takes docs-early-access files and merges them into docs-internal
+#
+# [end-readme]
+
+mv docs-early-access/assets assets/images/early-access
+mv docs-early-access/content content/early-access
+mv docs-early-access/data data/early-access

.github/actions-scripts/prune-for-preview-env.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# [start-readme]
+#
+# This script removes files that are unnecessary for our preview environments.
+# This is typically run before a docker build to reduce the size of the build context sent to docker
+#
+# [end-readme]
+
+# Remove all but the english search indexes
+find lib/search/indexes ! -name '*-en.json.br' ! -name '*-en-records.json.br' -maxdepth 1 -type f -delete
+
+# Translations are never tested in preview environments
+# but let's keep the empty directory.
+rm -rf translations
+mkdir translations
+
+# The assumption here is that a preview build will not
+# need these legacy redirects. Only the redirects from
+# front-matter will be at play.
+# These static redirects json files are notoriously large
+echo '[]' > lib/redirects/static/archived-frontmatter-fallbacks.json
+echo '{}' > lib/redirects/static/developer.json
+echo '{}' > lib/redirects/static/archived-redirects-from-213-to-217.json