Some tests in evergreen need different flags based on which buildvariant they run on. For example in csuite-tests-fast we want an additional flag "-LE sanitizer_long" on the ASan variant, but not the ubuntu2004 variant.

We're currently using a workaround by applying the sanitizer_long flag to all tests in the ASan variant as csuite-tests-fast is the only test that uses the variable, but we should find a long term solution that provides the proper config for specific buildvariant/test combinations.