Replace dateutils usage with datetime and oslo.utils

This cr fixes:
* Replaced ``dateutil.tz.tzlocal()`` and ``dateutil.tz.tzutc()`` with
  ``datetime.timezone`` built-in classes in audit controllers and
  continuous audit scheduling.

* Replaced ``dateutil.parser.parse()`` with
  ``oslo_utils.timeutils.parse_isotime()`` in the zone migration
  strategy for parsing datetime strings.

Closes-Bug: #2118404

Change-Id: I6d8a345fa4339a688769b147413dcdf3016bf4a0
Signed-off-by: Chandan Kumar (raukadah) <chkumar@redhat.com>

watcher/decision_engine/audit/continuous.py

@@ -21,7 +21,7 @@
 import datetime
 
 from croniter import croniter
-from dateutil import tz
+from datetime import timezone
 from oslo_utils import timeutils
 
 from watcher.common import context
@@ -123,7 +123,7 @@ class ContinuousAuditHandler(base.AuditHandler):
             'next_run_time') else 'run_date'
         # We should convert UTC time to local time without tzinfo
         trigger_args[time_var] = trigger_args[time_var].replace(
-            tzinfo=tz.tzutc()).astimezone(tz.tzlocal()).replace(tzinfo=None)
+            tzinfo=timezone.utc).astimezone().replace(tzinfo=None)
         self.scheduler.add_job(self.execute_audit, trigger,
                                args=[audit, audit_context],
                                name='execute_audit',

watcher/decision_engine/strategy/strategies/zone_migration.py

@@ -12,9 +12,8 @@
 # limitations under the License.
 #
 
-from dateutil.parser import parse
-
 from oslo_log import log
+from oslo_utils import timeutils
 
 from cinderclient.v3.volumes import Volume
 from novaclient.v2.servers import Server
@@ -893,7 +892,8 @@ class ComputeSpecSortFilter(BaseFilter):
                             reverse=True)
         elif sort_key == 'created_at':
             result = sorted(items,
-                            key=lambda x: parse(getattr(x, sort_key)),
+                            key=lambda x: timeutils.parse_isotime(
+                                getattr(x, sort_key)),
                             reverse=False)
 
         return result
@@ -959,7 +959,8 @@ class StorageSpecSortFilter(BaseFilter):
 
         if sort_key == 'created_at':
             result = sorted(items,
-                            key=lambda x: parse(getattr(x, sort_key)),
+                            key=lambda x: timeutils.parse_isotime(
+                                getattr(x, sort_key)),
                             reverse=False)
         else:
             result = sorted(items,