Revert "init: Add more diagnostics for signalfd hangs."

Revert commit 14f9c15e ("init: Add more diagnostics for signalfd
hangs") because:
* That commit was intented to help with root-causing b/223076262.
* The root cause of b/223076262 has been fixed (not blocking SIGCHLD
  in all threads in the init process).

Test: Treehugger
Change-Id: I586663ec0588e74a9d58512f7f31155398cf4f52
Signed-off-by: Bart Van Assche <bvanassche@google.com>