change assembly S3 prefix

@gretatuckute and @aalok-sathe want to change the prefix string for assemblies uploaded to S3, from `assy_` to e.g. `assembly_`

@jjpr-mit do you have any thoughts either way? `assy_` is currently the default in brainio.

https://github.com/brain-score/language/pull/32#discussion_r950189546

No file or test is named. Locate the code that uploads assemblies to S3 and check how the `assy_` default from brainio is applied; review the linked pull-request discussion for the intended replacement. Done means the agreed prefix is used consistently for assembly uploads.

Written by the indexing model from the issue text.