Run some tests sequentially to avoid exhausting available memory
Run some tests sequentially to avoid exhausting available memory

Some tests are run with "-Ytest-pickler" which uses a huge amount of
memory. By running these tests one by one when no other test is running,
we avoid running out of memory.

sjrd/dotty,som-snytt/dotty,dotty-staging/dotty,som-snytt/dotty,lampepfl/dotty,som-snytt/dotty,dotty-staging/dotty,som-snytt/dotty,sjrd/dotty,dotty-staging/dotty,sjrd/dotty,sjrd/dotty,lampepfl/dotty,dotty-staging/dotty,dotty-staging/dotty,lampepfl/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty,lampepfl/dotty