Cleanup create-route tests

[#68475822]
wait for instance on start is properly throttled

Signed-off-by: Aram Price <aprice@pivotallabs.com>
Merge remote-tracking branch 'origin/pr/188'
Decreate startup timeout in start_test.go

We feel rather strongly that increasing these timeouts is not really a
solution for making tests pass or fail. A better pattern would be to
apply a clock function as in the gateway or log_message_queue tests.

That would make these tests easier to maintain, faster and also less
flakey.