Remove return 0 script for transfers

[danielbate]

When instantiating a script transaction request, we set the script bytes to a simple script that returns 0.

fuels-ts/packages/account/src/providers/transaction-request/script-transaction-request.ts

Lines 67 to 68 in a071dce

	this.script = arrayify(script ?? returnZeroScript.bytes);
	this.scriptData = arrayify(scriptData ?? returnZeroScript.encodeScriptData());

For transfers this is redundant, and is unnecessarily increasing the cost of a transfer. fuel-core will allow us to keep the script field emty.