Bug: Hide Sign up if already signed up

[aguzmant103]

Report from user from Loom: https://www.loom.com/share/7da7aae4aa9e4a9cb48965e73e61f1a6?sid=ef95c42e-f387-48c2-84d6-4a0d68334082

[ctrlc03]

Seems like this is already fixed? @kittybest @crisgarner can you confirm please?

[ctrlc03]

so the issue here it's that the check if a user is signed up fails because it tries to fetch more than 1024 block at a time, so it will just throw. We need to fix this on MACI side https://github.com/privacy-scaling-explorations/maci/blob/dev/cli/ts/commands/signup.ts#L106

[ctrlc03]

fixed by #138