chore(bridge-withdrawer, composer): encode submission payload only once

[ethanoroshiba]

Summary

Changed submission logic to only encode retried transaction submissions to bytes once.

Background

Previously, Bridge Withdrawer and Composer utilized SequencerClientExt::submit_transaction_sync(), which encodes the transaction to bytes within the method. Within a retry configuration, this unnecessarily performs the conversion each time. These changes eliminate these superfluous encodings in favor of retrying with the same bytes each time.

Changes

• Changed submit_transaction_sync() calls to broadcast_tx_sync() calls.
• Moved Tx encoding to outside the retry logic.

Testing

Passing all tests, no additional ones needed since the functionality is the same.

Changelogs

No updates required.

Related Issues

closes #2050

[SuperFluffy]

I would push back on the primary change of this PR: it is a useful feature for a user not having to know how to transform a Transaction -> proto Transaction -> bytes in order to submit it to Sequencer.

With that said - what this PR does reveal is that there are some easy optimizations to be had in composer, bridge-withdrawer (and less so) auctioneer: we don't need to re-encode the bytes every time. It's sufficient to encode them once and resubmit the same bytes on certain kinds of errors (unless we need to bump the nonce, say).

[SuperFluffy]

This method is actually useful because here the caller need not know about how to transform a Transaction into a payload sequencer understands.

I would leave this.