[Clang][IFS][Test] Work around in-process cc1 ASAN issues #2.

Using the same strategy as c38e4252.

D69825 revealed (introduced?) a problem when building with ASan, and
some memory leaks somewhere. More details are available in the original
patch.

Looks like we missed one failing tests, this patch adds the workaround
to this test as well.

(cherry picked from commit e174da44)