A recent change [1] to show the real heartbeat timestamp from OVN agents
had a side effect of changing the timestamp format, which now includes a
timezone:
+-------------------+----------------------------------+
| Field | Value |
+-------------------+----------------------------------+
| last_heartbeat_at | 2023-02-23 14:12:07.471000+00:00 |
+-------------------+----------------------------------+
This unexpected format change causes some clients to fail to parse the
response to GET /v2.0/agents.
Normalise the format of the timestamp to remove timezone information.
Also remove the microsecond part, which was not done for OVN, but is
absent from other network agents.
[1] https://review.opendev.org/c/openstack/neutron/+/844179
Closes-Bug: #2008257
Change-Id: I75a37fb9b49a421e4524da6b56ef8362ceb6107b
827fbd01c3