Update buck srcs for tester harness

Differential Revision: D80125862

Pull Request resolved: #13344

Author: GregoryComer

backends/test/harness/TARGETS

@@ -4,10 +4,7 @@ oncall("executorch")
 
 runtime.python_library(
     name = "tester",
-    srcs = [
-        "__init__.py",
-        "tester.py",
-    ] + native.glob(["stages/*.py"]),
+    srcs = native.glob(["*.py", "stages/*.py"]),
     visibility = [
         "//executorch/...",
         "@EXECUTORCH_CLIENTS",