revert to old (non-resizable) thread pool

4 jobs for auto_choice in 14 minutes and 48 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build Docker
passed #1148415
build_docker

00:00:17

 
  Testing
passed #1148417
test_clang

00:13:19

passed #1148416
test_gcc

00:14:15

 
  Build Tarballs
passed #1148418
release

00:00:15