Increase delay for eternal-load test_load_fails test from 10 to 20 seconds (#4636)

Author: e673

cloud/blockstore/tools/testing/eternal_tests/eternal-load/bin/tests/test.py

@@ -51,7 +51,7 @@ def test_load_fails(scenario, engine, direct):
 
     with ThreadPoolExecutor(max_workers=1) as executor:
         future = executor.submit(__run_load_test, tmp_file.name, scenario, engine, direct)
-        time.sleep(10)
+        time.sleep(20)
 
         cnt = 0
         while future.running():