To reproduce:
1) Open attached project
2) Make sure Asset Pipeline is set to v2 in Editor Settings
3) Run the only test in Test Runner

Actual: The test takes ~20 seconds

4) Switch Asset Pipeline to v1 and restart the Editor
5) Run the only test in Test Runner

Expected: Now it takes only ~2 seconds

Reproduced in 2019.2.0f1, 2019.3.0a1, 2019.3.0b12, 2020.1.0a15

Notes:
v2 introduced in 2019.2.0a5, 2019.3.0a1
v2 became default/not experimental in 2019.3.0b5; 2020.1.0a3
v1 stopped being an option in 2020.1.0a16, it is still offered in latest 2019.3 (2019.3.0f3 of the time of writing, though it is marked "deprecated")