[clang][IFS][test] Temporary work around for in-process cc1 ASAN issues.

When using in-process cc1, the Clang Interface Stubs pipeline setup
exposes an ASAN bug. I am still investigating this issue but want to
green the bots for now. I don't think this is a huge issue since the
Clang Interface Stubs Driver setup code is the only code path that sets
up such a pipeline (ie N cc1's for N c files followed by another N cc1's
for to generate stub files for the same N c files).

This issue is being discussed in https://reviews.llvm.org/D69825.
If a resolution is not found soon, a bugzilla filling will be in order.