NMS-16978: Changed event's primary key to BIGINT

[christianpape]

• JIRA: https://opennms.atlassian.net/browse/NMS-16978

[dino2gnt]

Should the sequences now also CYCLE? I think 9 quintillion IDs makes that pretty safe.

opennms=# \d+ eventsnxtid
                        Sequence "public.eventsnxtid"
  Type  | Start | Minimum |       Maximum       | Increment | ***Cycles?*** | Cache
--------+-------+---------+---------------------+-----------+---------------+-------
 bigint |     1 |       1 | 9223372036854775807 |         1 | *** no ***    |     1

[cgorantla]

LGTM!