automated-local deployment with multiple HDDs

Submitted by a borg user via email:

borg 1.4.3 on Ubuntu 24.04.4 LTS / noble.

I have been using the howto on automatic borg backups here:
https://borgbackup.readthedocs.io/en/stable/deployment/automated-local.html

Even though i declared the right UUIDs of my two seperate usb backup disks in "backup.disks". Only on one it would start running as desired. Started the run.sh script by hand most of the time.

today i found the time to recheck and found this line thats added into the udev rules:

```
ACTION=="add", SUBSYSTEM=="block", ENV{ID_PART_TABLE_UUID}=="", TAG+="systemd", ENV{SYSTEMD_WANTS}+="automatic-backup.service"
```

This limits a systemd call to just one drive inserted. the one I used at first. Even if you add more drive UUIDs to the "backup.disks" file the backup won't start.

So i changed the udev rule to:
```
ACTION=="add", SUBSYSTEM=="block", TAG+="systemd", ENV{SYSTEMD_WANTS}+="automatic-backup.service"
```

This will run the run.sh script for every inserted block device (afaik) and will then run into the check for backup disks and fail unless it's an actual backup drive in there.

Valid fix or am i breaking something i can't see?

Start with deployment/automated-local.html and the referenced run.sh, automatic-backup.service, and udev rule. Compare the documented single-PTUUID trigger with the backup.disks handling for two drives, then reproduce the procedure with multiple disks. Done means confirming whether the rule is valid and updating the deployment behavior or documentation accordingly.

Written by the indexing model from the issue text.