Lower cronjob script verbosity

[guandalf]

Description
All cronjob scripts should not return any text except if there are errors, so the root mailbox does not get clogged and the administrator attention could be focused only on important stuff.

Example
I do not need to know that no new snapshot was created:

/etc/cron.hourly/btrfs-snp:
Cannot load Zend OPcache - it was already loaded
Create a readonly snapshot of '/media/myCloudDrive/ncdata' in '/media/myCloudDrive/ncdata/../ncp-snapshots/hourly_2022-12-05_161703'
Pruning old snapshots...
Delete subvolume (no-commit): '/media/myCloudDrive/ncp-snapshots/hourly_2022-12-04_161704'
snapshot hourly_2022-12-05_161703 generated
No new snapshot needed for daily in /media/myCloudDrive/ncdata
No new snapshot needed for weekly in /media/myCloudDrive/ncdata
No new snapshot needed for monthly in /media/myCloudDrive/ncdata

[guandalf]

There was a bug somewhere else that duplicated messages.
This is likely not needed.