Merge branch 'sp/refs-with-less-the-repository' into seen

Reduce the reference to the_repository in the refs subsystem.

* sp/refs-with-less-the-repository:
  refs/reftable-backend: drop uses of the_repository
  refs: remove the_hash_algo global state
  refs: add struct repository parameter in get_files_ref_lock_timeout_ms()

Author: gitster