[llvm-branch-commits] [not] Update disable-symbolization.test to work with internal shell (PR #157236)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/157236

This test is a special case as it executes two commands that are special
cased in the internal shell implementation. env runs entirely inside the
internal shell whereas not is handled specially, but still executed
externally. The internal shell does reorder execution of these though,
putting env commands before not which means we do not pick up
environment variables set by not.

These complications make it easier to just ensure that we invoke the
actual env binary (by calling it through bash) rather than using the
internal shell implementation.

Fixes #106627 by fixing the test, but without fixing the redirection
issue given the complexity does not seem justified.