Fix flaky recurrent timer test.

Do not rely on sleep in tests, but wait for the events to happen
before timeout. Set the timeout to be large enough (5s) so that the
tests are more stable.

Test: atest RecurrentTimerTest
Bug: 289759453
Change-Id: Iff271ca440426871ed3a798bab50b9532f9256f0
Merged-In: Iff271ca440426871ed3a798bab50b9532f9256f0
(cherry picked from commit 76d7fbf6)