Add _retry_server_directed_only mode for Retry-After header compliance#756

sd-db wants to merge 4 commits intodatabricks:maindatabricks/databricks-sql-python:mainfrom

sd-db:PECOBLR-1863/retry-server-directed-onlysd-db/databricks-sql-python:PECOBLR-1863/retry-server-directed-onlyCopy head branch name to clipboard