/lib/udev/rules.d/70-printers.rules is in system-config-printer-udev 1.4.6-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | # Low-level USB device add trigger
ACTION=="add", SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ENV{ID_USB_INTERFACES}=="*:0701??:*", TAG+="systemd", ENV{SYSTEMD_WANTS}="configure-printer@usb-$env{BUSNUM}-$env{DEVNUM}.service"
# Low-level USB device remove trigger
ACTION=="remove", SUBSYSTEM=="usb", ENV{ID_USB_INTERFACES}=="*:0701*:*", RUN+="udev-configure-printer remove %p"
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