Bug 1589612 - Remove remaining lsan_dir from WPT mach command. r=jgraham

Differential Revision: https://phabricator.services.mozilla.com/D49721

--HG--
extra : moz-landing-system : lando

testing/web-platform/mach_commands.py

@@ -76,9 +76,6 @@ class WebPlatformTestsRunnerSetup(MozbuildObject):
             if kwargs["host_cert_path"] is None:
                 kwargs["host_cert_path"] = os.path.join(cert_root, "web-platform.test.pem")
 
-        if kwargs["lsan_dir"] is None:
-            kwargs["lsan_dir"] = os.path.join(self.topsrcdir, "build", "sanitizers")
-
         if kwargs["reftest_screenshot"] is None:
             kwargs["reftest_screenshot"] = "fail"