Update from "flatcar_production_packet.ipxe" to "flatcar_production_equinix_metal.ipxe"

[krishjainx]

Update from "flatcar_production_packet.ipxe" to "flatcar_production_equinix_metal.ipxe"

In the current release, the "flatcar_production_packet.ipxe" file still mentions "Packet" instead of "Equinix Metal". To address this, let's rename the file from "flatcar_production_packet.ipxe" to "flatcar_production_equinix_metal.ipxe" for accurate representation.

Reference: https://github.com/flatcar/Flatcar/issues/483