Refactor plexon rawio to have same ids as plexon2

[h-mayorquin]

After #1541 Plexon2 ended up with the meaningful but unique stream_ids:

        stream_id_to_stream_name = {
            "WB": "WB-Wideband",
            "FP": "FPl-Low Pass Filtered",
            "SP": "SPKC-High Pass Filtered",
            "AI": "AI-Auxiliary Input",
        }

But in Plexon 1 we are using numbers instead: "1", "2", ...

This PR unifies them so they have the same stream_ids