* Test DHCP RENEW by the test client in the unmanaged variant.
* Add event IDs to log output of test client in order to prevent false positive
result in the managed variant.
* Let managed and unmanaged variant have separate string patterns for
'run_genode_until' because they already had different output and it will
differ even more as we don't want to test DHCP RENEW with the managed
variant.
* Delay first test client DHCP in order to fix unexpected sporadic initial IP
config.
* Remove some unnecessary code from the run script
Fixes#4460
9de4ecf8b6