Add basic backoff to stealing mechanism.

4 jobs from lock_free_task_stack in 3 minutes 40 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #2904
build_cmake

00:48

 
  Test
passed #2905
run_tests

00:40

 
  Sanitizer
passed #2907
run_address_sanitizer

01:18

passed #2906
run_thread_sanitizer

00:53