TestTransactionPoolOrderingAndClearing needs to be fixed and enabled

[algonautshant]

Summary

test/e2e-go/features/transactions/transactionPool_test.go-func TestTransactionPoolOrderingAndClearing(t *testing.T) {
test/e2e-go/features/transactions/transactionPool_test.go: t.Skip("test is flaky as of 2019-06-18")
This was disabled long time ago #45
Now never passes.

The tests stops one of the nodes, and expects the other node not to make any progress. However, the node continues to make progress.
This is not the main reason why the test is failing, but contributes to the stability of the test.
The other issue is that the test is expecting the transactions to be ordered by the fee, but they are not.

Similar issues are the following that need attention:
Those may need to be conditioned based on the protocol version.

test/e2e-go/features/transactions/transactionPool_test.go-func TestTransactionPoolExponentialFees(t *testing.T) {
test/e2e-go/features/transactions/transactionPool_test.go: t.Skip("new FIFO pool does not have exponential fee txn replacement")

test/e2e-go/restAPI/restClient_test.go-func TestClientPrioritizesPendingTransactions(t *testing.T) {
test/e2e-go/restAPI/restClient_test.go: t.Skip("new FIFO pool does not have prioritization")

Scope/Requirements

Fix the test and enable it.

Urgency/Relative Priority

This is not urgent, since it was disabled long time ago.
But it is important to fix it soon, otherwise the test will drift further away from the code.

[algonautshant]

This test was removed here: #2557