Correctly handle line markers

For better debuggability upon neverallow violations, this change leaves
line markers as-is.

* build_sepolicy filter_out tool leaves line markers as-is. It may cause
  markers to be redundant, so it also cleans up such markers.
* remove_line_marker property is removed as it is not needed.
* fixed odm_sepolicy.cil filtering.

Bug: 400544895
Test: check sepolicy artifacts
Change-Id: I793ffe728488422fc31de2705889869b2ea7d050
diff --git a/build/Android.bp b/build/Android.bp
index dbe17c8..ef898e8 100644
--- a/build/Android.bp
+++ b/build/Android.bp
@@ -32,3 +32,15 @@
         "version_policy",
     ],
 }
+
+python_test_host {
+    name: "sepolicy_file_utils_test",
+    srcs: [
+        "file_utils.py",
+        "file_utils_test.py",
+    ],
+    main: "file_utils_test.py",
+    test_options: {
+        unit_test: true,
+    },
+}