Revert "[libc++] Use proper shell escaping in the executors"

This reverts f8452ddfcc, which broke some bots. I'll figure out what's
wrong and commit it again.
diff --git a/libcxx/utils/ssh.py b/libcxx/utils/ssh.py
index f9bcabe..c7d8c97 100644
--- a/libcxx/utils/ssh.py
+++ b/libcxx/utils/ssh.py
@@ -15,7 +15,6 @@
 
 import argparse
 import os
-import pipes
 import posixpath
 import subprocess
 import sys
@@ -98,11 +97,10 @@
         # host by transforming the path of test-executables to their path in the
         # temporary directory, where we know they have been copied when we handled
         # test dependencies above.
-        commandLine = (pathOnRemote(x) if isTestExe(x) else x for x in commandLine)
         remoteCommands += [
             'cd {}'.format(tmp),
             'export {}'.format(' '.join(args.env)),
-            ' '.join(pipes.quote(x) for x in commandLine)
+            ' '.join(pathOnRemote(x) if isTestExe(x) else x for x in commandLine)
         ]
 
         # Finally, SSH to the remote host and execute all the commands.