The partition engine is not supported anymore, so instead of 'ER_FEATURE_NOT_AVAILABLE',
we should report 'ER_UNKNOWN_STORAGE_ENGINE' when detecting a non-natively partitioned
table while upgrading from 5.7.

This patch also makes main.dd_upgrade_test a big-test since it takes quite some time.

Change-Id: I562bb25375ba59f90feb15f182a7b3889f3ef035