Replace use of Promise.all to promise-fun library to limit concurrency.

https://github.com/digitalbazaar/bedrock-profile/blob/master/lib/profileAgents.js#L400

p-map is the right tool for this job: https://github.com/sindresorhus/p-map

Proper concurrency would be 10.  

The base async operation here appears to be `crypto.getRandomBytes` in edv-client
https://github.com/digitalbazaar/edv-client/blob/master/EdvClient.js#L931-L941
