TF2: Reenable tests that were disabled in TF2 by running them in graph mode. Mock expensive tf.hub calls. Disable some correctness tests that depend on tf.hub data.
TF2: Reenable tests that were disabled in TF2 by running them in graph mode. Mock expensive tf.hub calls. Disable some correctness tests that depend on tf.hub data.

PiperOrigin-RevId: 315158665
Change-Id: I64aaf780ff732637b2472cca0638e370929e5d87

tensorflow/gan,tensorflow/gan