Use tempest.lib code in tempest

Now that tempest_lib code is copied back into tempest, stop using
tempest_lib in tempest, and start using the copied code.

Remove the dependency to tempest_lib from requirements, and drop
the script to use tempest_lib in tempest. Add os-testr to the
test-requirements.

Partially implements bp tempest-lib-reintegration

Change-Id: I21ab5fe6349f72c98ac9f960a29bf62e813f8b1b
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index 96f32aa..ee21284 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -16,7 +16,6 @@
 import time
 
 from oslo_log import log as logging
-from tempest_lib import exceptions as lib_exc
 
 from tempest.api.compute import api_microversion_fixture
 from tempest.common import api_version_utils
@@ -25,6 +24,7 @@
 from tempest.common import waiters
 from tempest import config
 from tempest import exceptions
+from tempest.lib import exceptions as lib_exc
 import tempest.test
 
 CONF = config.CONF