Remove flaky verification in ALTER/CREATE table tests

This fixes the flaky ALTER/CREATE tests by removing a verification step that
didn't add value and was non-deterministic. The verficiation step that was
removed verified that CREATE/ALTER set the appropriate file format by
changing the format to something that didn't match the underlying data files,
then attempting to read the data. This is already covered by the positive
test case where the file format is changed to match the underlying data.

Change-Id: I66f485405234f472f3b83f3e776bf7f2c10de874
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1379
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins