avocado.test: Remove unused imports

Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/test.py

@@ -5,9 +5,6 @@ framework tests.
 
 import logging
 import os
-import sys
-import time
-import traceback
 from avocado.core import data_dir
 from avocado.core import exceptions
 from avocado.utils import process