[Chore]: Add backoff and jitter to Emily internal retry

[matteojug]

Chore - Add backoff and jitter to Emily internal retry

1. Description

In Emily we had a retry mechanism in case we hit version conflict when updating records on DynamoDB:

sbtc/emily/handler/src/database/accessors.rs

Lines 174 to 196 in 39b961f

	for _ in 0..retries {
	// Get original deposit entry.
	let deposit_entry = get_deposit_entry(context, &update.key).await?;
	// Return the existing entry if no update is necessary.
	if update.is_unnecessary(&deposit_entry) {
	return Ok(deposit_entry);
	}
	// Make the update package.
	let update_package: DepositUpdatePackage =
	DepositUpdatePackage::try_from(&deposit_entry, update.clone())?;
	// Attempt to update the deposit.
	match update_deposit(context, &update_package).await {
	Err(Error::VersionConflict) => {
	// Retry.
	continue;
	}
	otherwise => {
	return otherwise;
	}
	}
	}
	// Failed to update due to a version conflict
	Err(Error::VersionConflict)

(also happens in add_chainstate_entry_with_retry and pull_and_update_withdrawal_with_retry).

We should add some backoff and jitter to reduce congestion and machine load.