[Chapel Merge] Use `CHPL_LLVM=bundled` for make install testing

Branch: refs/heads/master
Revision: df49236
Author: ronawho
Log Message:

Merge pull request #17637 from ronawho/use-llvm-make-install

Use CHPL_LLVM=bundled for make install testing

[reviewed by @daviditen]

Our testing for make install intentionally doesn't source our
common.bash scripts that set up paths to llvm and other things because
it's trying to test the install from a user perspective. We now have to
set CHPL_LLVM to some value, so choose bundled since that's what we're
expecting to become the default.

Modified Files:
M util/buildRelease/test_install.bash

Compare: https://github.com/chapel-lang/chapel/compare/616dc39c727e...df492363e3f4