compress: fix an internal error when a specific debug log is enabled
While iterating over the recent 69684e16d8,
series I shot myself in the foot by defining `algorithm_to_name(algorithm::none)`
to be an internal error, and later calling that anyway in a debug log.
(Tests didn't catch it because there's no test which simultaneously
enables the debug log and configures some table to have no compression).
This proves that `algorithm_to_name` is too much of a footgun.
Fix it so that calling `algorithm_to_name(algorithm::none)` is legal.
In hindsight, I should have done that immediately.
Fixes#23624
Fix for recently-added code, no backporting needed.
Closesscylladb/scylladb#23625
* github.com:scylladb/scylladb:
test_sstable_compression_dictionaries: reproduce an internal error in debug logging
compress: fix an internal error when a specific debug log is enabled
We adjust all of the simple cases of cluster tests so they work
with `rf_rack_valid_keyspaces: true`. It boils down to assigning
nodes to multiple racks. For most of the changes, we do that by:
* Using `pytest.mark.prepare_3_racks_cluster` instead of
`pytest.mark.prepare_3_nodes_cluster`.
* Using an additional argument -- `auto_rack_dc` -- when calling
`ManagerClient::servers_add()`.
In some cases, we need to assign the racks manually, which may be
less obvious, but in every such situation, the tests didn't rely
on that assignment, so that doesn't affect them or what they verify.
