[JENKINS-13349] Not fire timout repeatedly with NoActivityTimeOutStrategy

Additional fix for #17 .

#17 provides triggering timeout operations when no activity from the last console output.
#18 provides defining operations performed when timeout, which results to allow continue the build even when timeout.

I found that when a build continues even when timeout, #17 causes trigger timeout operations repeatedly.

This change makes timeout operation triggered by `NoActivityTimeOutStrategy` (#17) only once.

I think this change also fixes [JENKINS-3917] (https://issues.jenkins-ci.org/browse/JENKINS-3917), but I'm not sure.