Decouple kubespray-defaults from download (#10626)

* Decouple role kubespray-defaults from download

Avoids doing re-importing the download role on every invocation of
kubespray-defaults (and skipping everything).

This has a measurable effect on playbook performance.

* Update docs refering to moved download defaults

scripts/download_hash.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 
 # After a new version of Kubernetes has been released,
-# run this script to update roles/download/defaults/main/main.yml
+# run this script to update roles/kubespray-defaults/main/download.yml
 # with new hashes.
 
 import hashlib
@@ -10,7 +10,7 @@ import sys
 import requests
 from ruamel.yaml import YAML
 
-MAIN_YML = "../roles/download/defaults/main/main.yml"
+MAIN_YML = "../roles/kubespray-defaults/main/download.yml"
 
 def open_main_yaml():
     yaml = YAML()

scripts/download_hash.sh

@@ -6,7 +6,7 @@ if [[ ${DEBUG:-false} == "true" ]]; then
     set -o xtrace
 fi
 
-checksums_file="$(git rev-parse --show-toplevel)/roles/download/defaults/main/checksums.yml"
+checksums_file="$(git rev-parse --show-toplevel)/roles/kubespray-defaults/defaults/main/checksums.yml"
 downloads_folder=/tmp/kubespray_binaries
 
 function get_versions {