[sai-trading] Make sample_txs JSON file generation more deterministic to keep unnecessary changes from surfacing in the git history

[Unique-Divine]

The Ask

During the setup script that deploys the Sai wasm bytecode and EVM interface,
several JSON files are accessed and partially generated for use as arguments to
initialize contracts, markets, and trades. Some of these files are dynamic and
change between successive runs of the script. We should separate the dynamic
parts out so that the changes don't get added in as junk commits in the repo.

Solution

Run a local network in the background with just localnet

Then, run sai-trading/e2e_deploy.ts a few times.

cd sai-trading
just i
just e2e-deploy
just e2e-deploy
just e2e-deploy

You can see which fields are dynamic based on the resulting changes in the
sai-trading/sample_txs directory.