replace `TRANSACTION_CONFIRMATION_WAIT_SECS` with receipt confirmations

[wjmelements]

ok I see you do a similar thing elsewhere (TRANSACTION_CONFIRMATION_WAIT_SECS). You can fix all of those in a separate PR. That should improve the setup time by a few minutes.

Originally posted by @wjmelements in #57 (comment)

We want to avoid sleeping between transactions to reduce the time it takes to run everything.

cast send waits for confirmation by default. Might need --confirmations 2 if the state isn't updated after 1 confirmation.

Instead of waiting between transactions, increment nonce and pass it to cast --async when possible. Only wait for the last transaction in a sequence. For deploying transactions, you can calculate the contract address ahead of time via sender+nonce, so it is not necessary to await a transaction just to obtain an address.

Separately, the devnet block time should be configurable. Please ensure it has been set to some low value.

[redpanda-f]

I would say configurability of devnet block time should not be scoped in here. This is because those changes have implication on Lotus and Curio codebases alongwith synapse changes (I think) as well.

This was attempted before and was not straightforward.

Added a separate task: #60