Revert "[lldb] Fix TestSettings.test_pass_host_env_vars on windows"

This reverts commit because of test failures in TestHelloWorld.

It seems that this test (specifically running "ls" as a platform shell
command) depended on the implicit passing of the host environment.

The fix should be fairly simple (inherit the environment explicitly),
but it may take me a while to figure where exactly to do that. Revert
while I am figuring that out.