[Driver][test] Don't assume integrated-as

The tests of fdebug-compilation-dir and -ffile-compilation-dir for `-x
assembler` are assuming integrated-as.
If the platform set the no-itegrated-as by default (eg: AIX for now), then this test will
fail.

Add the -integrated-as to aviod relying on the platform defaults.

Reviewed By: thakis

Differential Revision: https://reviews.llvm.org/D102647