rpk.tune_* options in configs/default.j2 template for redpanda_broker needs to be configurable

[hcoyote]

https://github.com/redpanda-data/redpanda-ansible-collection/blob/60660d3cb84d69f4ded523596adaf71250f7c0c3/roles/redpanda_broker/templates/configs/defaults.j2#L50-L75

we've previously had all the rpk tuner configs hard set to true because that's what we wanted in a production setup by default. We've now gotten to the point that on some hardware we need to fine tune this when ansible is deploying.

See thread https://redpandadata.slack.com/archives/C03H26FHJQL/p1708974887034249