tests(acme) change ttl tests to use 2 secs ttl instead of 1 sec
tests(acme) change ttl tests to use 2 secs ttl instead of 1 sec

### Summary

Our CI has reported some flakiness on these tests, thus I decided
that perhaps it helps to change the `ttl` from 1 sec to 2 sec on
ttl related tests.

Kong/kong,Kong/kong,Kong/kong