move tests that are sub 3 minutes out of long running classification

[spoonincode]

Move tests that execute in less than 3 minutes out of the long_running_tests bucket and in to the nonparallelizable_tests bucket.

Long running tests are also moved to a new runner type, enf-x86-lowtier. This is an 8vCPU 16GB instance. Similar to NP tests, most of these long running tests idle around so I am "over subscribing" them for now. We can always bump up the resources on this runner type if needed. Like midtier, enf-x86-lowtier is running on the "give me whatever you got tier" which seems to be getting rather old Broadwell CPUs.

🚨 This completely removes nodeos_sanity_lr_test. afaict it's the exact same test as the non-lr test; am I missing something? 🚨

add_test(NAME nodeos_sanity_test COMMAND tests/nodeos_run_test.py -v --sanity-test --clean-run --dump-error-detail WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
add_test(NAME nodeos_sanity_lr_test COMMAND tests/nodeos_run_test.py -v --sanity-test --clean-run --dump-error-detail WORKING_DIRECTORY ${CMAKE_BINARY_DIR})

A manual workflow run on this branch with LR tests clutched in is at
https://github.com/AntelopeIO/leap/actions/runs/2966597472