[lldb] Fix TestEchoCommands.test again

In 7f01f785 [lldb] update TestEchoCommands -- I fixed this test,
but not on windows, becuase I used  some unix shell syntax that
doesn't work with cmd.exe.   Fixed it so it will work in both.
Test logic is the same.

This is a trivial fix, so bypassing review to get the build clean again
ASAP.