Migrate Semaphore v3 to v4 in the Bandada cached group

[vplasencia]

Description

Right now Semaphore v4 is being used for the on-chain groups and the Bandada boilerplate but it would be nice to also use it for the cached groups. This way it's no longer necessary to choose the size of the group since it will grow dynamically thanks to the LeanIMT supported by Semaphore v4.

More context

Bandada cached groups: https://github.com/bandada-infra/bandada/blob/main/apps/api/src/app/groups/groups.service.ts#L13

The cached groups are used to maintain an IMT per group with all the members to make it easier for people to generate merkle proofs. This is especially useful for very large groups where generating a merkle proof in a browser can take long, or may not be feasible.