Remove unused persist_library.sh and restore_library.sh (#6112)

These scripts managed an rsync-based Library/ cache to /tmp/eagle0/ but
are never called from any workflow. Library/ caching now relies on
clean: false preserving the working directory between self-hosted runs.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

ci/github_actions/persist_library.sh

@@ -1,33 +0,0 @@
-#!/bin/bash
-#
-# Persist Unity Library/ cache to persistent storage
-#
-# Environment variables:
-#   UNITY_CACHE_PLATFORM - Platform identifier (e.g., "mac", "windows")
-#                          Defaults to "mac" if not set
-#
-# Note: Library/Bee/ is excluded because it contains DAG files with hardcoded
-# file paths that become stale when project files change. This prevents
-# "Data at the root level is invalid" XML errors from stale references.
-
-set -uxo pipefail
-
-PLATFORM="${UNITY_CACHE_PLATFORM:-mac}"
-CACHE_DIR="/tmp/eagle0/Library-${PLATFORM}"
-
-/bin/echo "persist Library/ to $CACHE_DIR (excluding Bee/)"
-
-# rsync may exit with code 23 ("partial transfer due to error") if Unity's
-# temporary files vanish during the copy. This is acceptable for a cache.
-/usr/bin/rsync -rtlDvq --exclude='Bee/' src/main/csharp/net/eagle0/clients/unity/eagle0/Library/ "$CACHE_DIR/"
-rsync_exit=$?
-
-if [ $rsync_exit -eq 0 ]; then
-    exit 0
-elif [ $rsync_exit -eq 23 ]; then
-    echo "Warning: rsync exited with 23 (some files vanished during copy). This is expected for Unity temp files."
-    exit 0
-else
-    echo "Error: rsync failed with exit code $rsync_exit"
-    exit $rsync_exit
-fi

ci/github_actions/restore_library.sh

@@ -1,16 +0,0 @@
-#!/bin/bash
-#
-# Restore Unity Library/ cache from persistent storage
-#
-# Environment variables:
-#   UNITY_CACHE_PLATFORM - Platform identifier (e.g., "mac", "windows")
-#                          Defaults to "mac" if not set
-
-set -euxo pipefail
-
-PLATFORM="${UNITY_CACHE_PLATFORM:-mac}"
-CACHE_DIR="/tmp/eagle0/Library-${PLATFORM}"
-
-/bin/echo "restore Library/ from $CACHE_DIR"
-/bin/mkdir -p "$CACHE_DIR"
-/usr/bin/rsync -rtlDvq "$CACHE_DIR/" src/main/csharp/net/eagle0/clients/unity/eagle0/Library/