Testing the Minting process in Mainnet or Perftestnet

### Problem description
In the corse of https://github.com/hashgraph/hedera-sdk-js/discussions/1061 Guardian team attempted, unsuccessfully, to reduce the time it took to mint large number of tokens within a realistic timeframes.

One of the theories on why the performance is low is that the general 'raw' testnet performance is low - due to a small number of nodes and their configuration.

Also see #363

### Requirements

- Test performance of token mint in a real world network or as close to it as possible.
- Experiment with splitting the submitting transaction and requesting results into different threads.

### Definition of done
Reducing the overall minting time

### Acceptance criteria
Conclusively determine the performance of Guardian (NFT) minting