chore(tiering_test): tune memory settings to be below 6GB (#5345)

Signed-off-by: Roman Gershman <[email protected]>

Author: romange

tests/dragonfly/tiering_test.py

@@ -96,24 +96,25 @@ async def run(sub_ops):
     {
         "proactor_threads": 2,
         "tiered_prefix": "/tmp/tiered/backing_master",
-        "maxmemory": "4G",
+        "maxmemory": "2.0G",
         "cache_mode": True,
-        "tiered_offload_threshold": "0.2",
+        "tiered_offload_threshold": "0.1",
+        "tiered_low_memory_factor": "0.2",
         "tiered_storage_write_depth": 100,
     }
 )
 async def test_full_sync(async_client: aioredis.Redis, df_factory: DflyInstanceFactory):
     replica = df_factory.create(
         proactor_threads=2,
         cache_mode=True,
-        maxmemory="4G",
+        maxmemory="2.0G",
         tiered_prefix="/tmp/tiered/backing_replica",
         tiered_offload_threshold="0.2",
         tiered_storage_write_depth=1000,
     )
     replica.start()
     replica_client = replica.client()
-    await async_client.execute_command("debug", "populate", "3000000", "key", "2000")
+    await async_client.execute_command("debug", "populate", "1700000", "key", "2000")
     await replica_client.replicaof(
         "localhost", async_client.connection_pool.connection_kwargs["port"]
     )