build: retry external binary downloads a few times (#24110)

script/update-external-binaries.py

@@ -97,10 +97,15 @@ def sha256(file_path):
   return hash_256.hexdigest()
 
 
-def download_binary(base_url, sha, binary_name):
+def download_binary(base_url, sha, binary_name, attempt=3):
   full_url = '{0}/{1}/{2}'.format(base_url, sha, binary_name)
-  temp_path = download_to_temp_dir(full_url, filename=binary_name, sha=sha)
-  return temp_path
+  try:
+    temp_path = download_to_temp_dir(full_url, filename=binary_name, sha=sha)
+    return temp_path
+  except Exception as e:
+    if attempt == 1:
+       raise e
+    return download_binary(base_url, sha, binary_name, attempt - 1)
 
 
 def validate_sha(file_path, sha):