IMPALA-3491: Use unique_database fixture in test_views_compatibility.
IMPALA-3491: Use unique_database fixture in test_views_compatibility.

Testing: Ran the test locally. It was already possible to run the
test in parallel before.

Change-Id: I68a1349276c90a42c238bed40a1c7c221199a67a
Reviewed-on: http://gerrit.cloudera.org:8080/3009
Reviewed-by: Alex Behm <fe1626037acfc2dc542d2aa723a6d14f2464a20c@cloudera.com>
Tested-by: Internal Jenkins

cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala