refactor: small fixes of tests

Signed-off-by: Stepan Bagritsevich <stefan@dragonflydb.io>

tests/dragonfly/memory_test.py

@@ -119,17 +119,16 @@ async def test_rss_oom_ratio(df_factory: DflyInstanceFactory, admin_port):
     }
 )
 async def test_cache_eviction_with_rss_deny_oom(
+    client: aioredis.Redis,
     df_server: DflyInstance,
 ):
     """
     Test to verify that cache eviction is triggered even if used memory is small but rss memory is above limit
     """
 
-    client = df_server.client()
-
     max_memory = 256 * 1024 * 1024  # 256 MB
-    first_fill_size = int(0.15 * max_memory)  # 20% of max memory
-    second_fill_size = int(0.3 * max_memory)  # Another 20% of max memory
+    first_fill_size = int(0.2 * max_memory)  # 15% of max memory
+    second_fill_size = int(0.35 * max_memory)  # Another 20% of max memory
     rss_increase_size = int(0.3 * max_memory)  # 30% of max memory
 
     key_size = 1024  # 1 mb