Fixed tests timing out when CUJ is set to stay in app until next CUJ.

This was caused by idle time in CUJ set to hit right up to the timeout
deadline. This especially became a problem after LongevityClassRunner
put @AfterClass into @After, which resulted in @AfterClass not having
time to execute before hitting the timeout.

Bug: 144958271
Test: atest LongevityPlatformLibTests:ScheduledScenarioRunnerTest (issue
reproduced in test and verified fixed)
Change-Id: Iee3891781307953ec9f2f65ea5ece57e5c5e24a6
(cherry picked from commit 5fcd9c0bf986ae119549ec43010c081c9c5e9765)