Remove unnecessary abstract_task reference.

4 jobs from pure_fork_join in 38 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #3104
build_cmake

00:20

 
  Test
failed #3105
run_tests

00:17

 
  Sanitizer
skipped #3107
run_address_sanitizer
skipped #3106
run_thread_sanitizer
 
Test run_tests
compilation terminated.
make[2]: *** [app/playground/CMakeFiles/playground.dir/main.cpp.o] Error 1
app/playground/CMakeFiles/playground.dir/build.make:62: recipe for target 'app/playground/CMakeFiles/playground.dir/main.cpp.o' failed
make[1]: *** [app/playground/CMakeFiles/playground.dir/all] Error 2
CMakeFiles/Makefile2:191: recipe for target 'app/playground/CMakeFiles/playground.dir/all' failed
make: *** [all] Error 2
Makefile:140: recipe for target 'all' failed
./ci_scripts/run_tests.sh: line 9: ./bin/tests: No such file or directory
ERROR: Job failed: exit code 1