Do not log PVF prunning every hour (#4372)

This lowers the level of the PVF pruning.

Closes https://github.com/paritytech/polkadot/issues/4361
28 jobs for master in 50 minutes and 26 seconds (queued for 9 seconds)
Name Stage Failure
failed
zombienet-tests-malus-dispute-valid Deploy


exit code 4
+ EXIT_STATUS=4
+ set +x

2021-11-27 01:58:19 - INFO - Exit status is 4
Cleaning up file based variables
ERROR: Job failed: command terminated with exit code 1
failed
zombienet-tests-parachains-smoke-test Deploy


exit code 1
+ EXIT_STATUS=1
+ set +x

2021-11-27 01:58:07 - INFO - Exit status is 1
Cleaning up file based variables
ERROR: Job failed: command terminated with exit code 1