Change the Godzilla vs. Megalon tags

BUR #55000 has been rejected.

create alias godzilla_vs._megalon_(1973) -> godzilla_vs._megalon
create alias godzilla_vs._megalon_(2023) -> godzilla_vs._megalon_(2023_short)

The 1973 movie came first, so it can just be called Godzilla vs. Megalon.
The 2023 film that causes confusion is a short so it can be called Godzilla vs. Megalong (2023 short)

We already went over this in topic #30272. They both need to be qualified because "Godzilla vs. Megalon" could mean either one.

The bulk update request #55000 (forum #419084) has been rejected by @evazion.