Remove unused data structures (old work stealing deques).

If they are required in future iterations they can be re-added from the history, however,
for now it only confuses project users as it is not clear which data structures are actually in use.
Status Job ID Name Coverage
  Build
passed #4039
build_cmake

01:08

 
  Test
passed #4040
run_tests

01:09

 
  Sanitizer
passed #4041
run_address_sanitizer

02:21