Update et_replay reference to latest module path.

Summary:
For changes originating in facebookresearch/param#133.

ET replay package modules are getting flatter and simpler to import. Updating references in HTA to be the same.

Differential Revision: D59748145

hta/common/execution_trace.py

@@ -21,11 +21,11 @@
 
 try:
     # Import path in github due to submodule
-    from et_replay.lib.execution_trace import ExecutionTrace
+    from et_replay.execution_trace import ExecutionTrace
 except ImportError:
     try:
         # Import path in fbcode
-        from param_bench.et_replay.lib.execution_trace import ExecutionTrace
+        from param_bench.et_replay.execution_trace import ExecutionTrace
     except ImportError:
         IMPORT_EXECUTION_TRACE_SUCCESSFULLY = False
         pass