Improve handling timeout while preloading tx

[hayarobi]

In file contract/contract.go, there can be a bug while executing preloaded tx executor. Investigate and fix it if needed.

		// create a new context
		// FIXME need valid context
		ctx := NewVmContext(context.Background(), bs, nil, nil, receiver, contractState, txBody.GetAccount(), tx.GetHash(), request.bi, "", false, false, receiver.RP(), request.preloadService, txBody.GetAmountBigInt(), txBody.GetGasLimit(), txBody.Type == types.TxType_FEEDELEGATION)

[kroggen]

If preloaded txns were removed, I suspect this issue can be closed

[kroggen]

@hayarobi Can this be closed?