This makes sub packages of e2e test framework to use log functions
of core framework instead for avoiding circular dependencies.
NOTE: test/e2e/framework/ssh will make circular dependencies if
updating it. It is necessary to solve the issue in advance
before this work.
ConfirmStatefulPodCount() was used at e2e statefulset test only,
and that added dependency on another sub framework to statefulset
sub framework. This moves ConfirmStatefulPodCount() to the e2e test
for clean dependency.
