Ansible fails when enabling TLS due to safe restart

[tmgstevens]

The code for safe restart uses rpk cluster maintenance enable {{ node_id }} which unfortunately uses the new rpk settings before TLS is enabled.

We either need a way to single-thread the whole of the last few plays (to ensure that maintenance mode is enabled, the node is restarted and then MM disabled all in a single action), or we need to nestle the updating of the redpanda.yaml file into that single shell command.

When I wrote this I couldn't find a way of having a block with throttle set within a role.