AIX - tweak jenkins agent startup after reboot

[mhdawson]

We almost never reboot the AIX machines because we've been advised that it is best practice not to reboot unless necessary.

After the latest system maintenance (#1369) there was a failure in one of the tests which was resolved by restarting the jenkins agent after logging in. We probably need to tweak how the agent is started on reboot in order to avoid this in the future. See nodejs/node#21451 for details of the failure.

[MylesBorins]

can we get another restart of the agent? The same test is failing again on the 8.x release line

[addaleax]

nodejs/node#25226 should fix the test in question.