"shell" step doesn't support check mode, which currently leads to failures,
when Ansible is being run in check mode (because Ansible doesn't run command,
assuming that command might have effect, and no "rc" or "output" is registered).
Setting "check_mode: no" allows to run those "shell" commands in check mode
(which is safe, because those shell commands doesn't have side effects).
Related bug: https://github.com/ansible/ansible/issues/15405
Uses tar and register because synchronize module cannot sudo on the
remote side correctly and copy is too slow.
This patch dramatically cuts down the number of tasks to process
for cert synchronization.
