* [CI] Make E2E tests run in multiple JDK versions

* Polish

* Use new e2e-container version number

* Install socat in reboot case

* Fix reboot case

* Polish

* Reorganize jobs

The current latency of the test service is too slow, causing it's not counted and
the query result is 0, this patch increases the latency intentionally by sleeping
1 second

* Support upgrade backend w/o rebooting agents