test: add cluster tests for write CL guardrails

Most of the functionality is tested in cqlpy tests located in
`test_guardrail_write_consistency_level.py`. Add two tests
that require the cluster framework:

- `test_invalid_write_cl_guardrail_config` checks the node startup
  path when incorrect `write_consistency_levels_warned` and
  `write_consistency_levels_disallowed` values are used.
- `test_write_cl_default` checks the behavior of the default
  configuration using a multi-node cluster.

Tests execution time:
 - Dev: 10s
 - Debug: 18s

Refs: SCYLLADB-259

test/cluster/test_guardrails.py

@@ -5,13 +5,17 @@
 #
 
 import logging
-
 import pytest
+import time
+
+from cassandra import ConsistencyLevel
 from cassandra.protocol import ConfigurationException, InvalidRequest
+from cassandra.query import SimpleStatement
 
 from test.pylib.async_cql import _wrap_future
-from test.pylib.manager_client import ManagerClient
+from test.pylib.manager_client import ManagerClient, wait_for_cql_and_get_hosts
 from test.pylib.util import unique_name
+from test.cluster.util import new_test_keyspace
 
 logger = logging.getLogger(__name__)
 
@@ -97,3 +101,48 @@ async def test_all_rf_limits(manager: ManagerClient):
             await create_ks_and_assert_warning(cql, query, ks_name, ["warn", "max", "replication", "factor", str(MAX_WARN_THRESHOLD), dc, str(rf)])
         else:
             await create_ks_and_assert_warning(cql, query, ks_name, [])
+
+
+@pytest.mark.asyncio
+async def test_invalid_write_cl_guardrail_config(manager: ManagerClient):
+    """A node configured with invalid values for write_consistency_levels_warned
+    and write_consistency_levels_disallowed should still start and respond to
+    CQL queries. The invalid values cause yaml-cpp conversion errors logged
+    during startup."""
+    cfg = {
+        "write_consistency_levels_warned": ["INVALID_CL", "BOGUS"],
+        "write_consistency_levels_disallowed": ["NOT_A_CL"],
+    }
+    manager.ignore_log_patterns.append("bad conversion : write_consistency_levels_warned")
+    manager.ignore_log_patterns.append("bad conversion : write_consistency_levels_disallowed")
+
+    server = await manager.server_add(config=cfg)
+    log = await manager.server_open_log(server.server_id)
+
+    assert len(await log.grep("bad conversion : write_consistency_levels_warned")) > 0
+    assert len(await log.grep("bad conversion : write_consistency_levels_disallowed")) > 0
+
+    cql, _ = await manager.get_ready_cql([server])
+    rows = await cql.run_async("SELECT * FROM system.local")
+    assert len(rows) == 1
+
+@pytest.mark.asyncio
+async def test_write_cl_default(manager: ManagerClient):
+    """Test checks that the current implementation doesn't cause
+    any warning nor failure for the default configuration."""
+
+    servers = await manager.servers_add(3, auto_rack_dc="dc1")
+    cql, _ = await manager.get_ready_cql(servers)
+
+    async with new_test_keyspace(manager, "WITH replication = {'class': 'NetworkTopologyStrategy', 'replication_factor': 3}") as ks:
+        await cql.run_async(f"CREATE TABLE {ks}.t (pk int PRIMARY KEY, v int)")
+
+        all_cls = [ConsistencyLevel.ANY, ConsistencyLevel.ONE, ConsistencyLevel.LOCAL_ONE,
+                ConsistencyLevel.TWO, ConsistencyLevel.THREE, ConsistencyLevel.QUORUM,
+                ConsistencyLevel.ALL, ConsistencyLevel.LOCAL_QUORUM, ConsistencyLevel.EACH_QUORUM]
+
+        for cl in all_cls:
+            stmt = SimpleStatement(f"INSERT INTO {ks}.t (pk, v) VALUES (1, 1)", consistency_level=cl)
+            ret = cql.execute_async(stmt)
+            await _wrap_future(ret)
+            assert not ret.warnings, f"Expected no warning for {ConsistencyLevel.value_to_name[cl]}, got {ret.warnings}"