iorap: Terminate iorapd process when both tracing and prefetching are off.

Purge spam log when iorapd process is not alive.
Turn off the Iorap Service when both tracing and prefetching are not
alive.

Bug: 174588448
Test: set the flags via mendel and check the log
Change-Id: I8d4e0c869dec5e7dc5016622b154aef46e1d4f02
(cherry picked from commit 11b592be)