Dropped the sandbox.

- It wasn't worth the complexity. It was only useful when running the
  python profile tool, which executes python scripts. But that tool
  isn't very useful when run against normal scripts. It has been
  removed too.
- The sandbox also wasn't working inside snaps, appimages,
  systemd-nspawn or chroots.

worker_test.py

@@ -27,9 +27,9 @@ class WorkerTestCase(unittest.TestCase):
         shutil.rmtree(self.temp_dir)
         os.chdir(self.original_working_dir)
 
-    def _test_worker(self, is_sandboxed):
+    def test_run_job(self):
         loop = asyncio.get_event_loop()
-        worker_ = worker.Worker(is_sandboxed, False, False)
+        worker_ = worker.Worker(False, False)
         loop.run_until_complete(worker_.create_process())
         future = worker_.run_tool("foo", tools.metadata)
         status = loop.run_until_complete(future)
@@ -37,12 +37,6 @@ class WorkerTestCase(unittest.TestCase):
         result_path = os.path.join(tools.CACHE_PATH, "foo-metadata")
         self.assertTrue(os.path.exists(result_path))
 
-    def test_run_job_without_sandbox(self):
-        self._test_worker(False)
-
-    def test_run_job_with_sandbox(self):
-        self._test_worker(True)
-
 
 if __name__ == "__main__":
     unittest.main()