Pi-Hole is already set up to update gravity weekly on Sunday morning at a time between 0300 and 0500 (0309 in your case). The random time avoids excessive server queries at once from all Pi-Hole users.
Commenting out these cron lines disables these features.
Your proposed system update cron should be in addition to the existing Pi-Hole cron script, rather than replacing the script.
This cron is not necessary. On the master branch, changes occur infrequently and are announced and would be shown as an update available on your dashboard through the existing version checks.