[not][test] Fix disable-symbolization.test when 'printenv' is not available

On Windows, 'env' or 'printenv' may not exist.

Also switch back to 'env' which is specified by POSIX.1-2017. 'printenv' is not
standard (I picked it because 'printenv' exists on GnuWin32 but 'env' does not).

Reviewed By: zequanwu

Differential Revision: https://reviews.llvm.org/D86496