[Trivial] bls_worker: Fix members initialization order in Aggregators
[Trivial] bls_worker: Fix members initialization order in Aggregators

Also fix review nits:

- replace hardware_concurrency() with GetNumCores()
- remove code duplication for (Async)VerifyContributionShare
PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet