Use tenant's pitr_interval instead of hardroded 0 in the command.

Adjust python tests that use the

test_runner/performance/test_random_writes.py

@@ -8,7 +8,6 @@ from fixtures.log_helper import log
 import psycopg2.extras
 import random
 import time
-from fixtures.utils import print_gc_result
 
 
 # This is a clear-box test that demonstrates the worst case scenario for the