Disable logging for unittests
Disable logging for unittests

Summary:
When you run tests, they shouldn't be writing to the log.  This
Disables logging in set up of BaseTestCase and reenables in tear_down

Test Plan: checked that nothing was written to the log

Reviewers: anu, cwallin

Reviewed By: cwallin

Differential Revision: https://phabricator.td.teradata.com/D253

Svjard/presto-admin,Svjard/presto-admin,prestodb/presto-admin,prestodb/presto-admin