fs_mgr: Fix executable path in clean_scratch_files.

Bug: 154071877
Test: no error log on startup
Change-Id: I84c627011992eed6952697e7260051006b1c10d0
Merged-In: I84c627011992eed6952697e7260051006b1c10d0
diff --git a/fs_mgr/clean_scratch_files.rc b/fs_mgr/clean_scratch_files.rc
index 738d1aa..25a7e69 100644
--- a/fs_mgr/clean_scratch_files.rc
+++ b/fs_mgr/clean_scratch_files.rc
@@ -1,2 +1,2 @@
 on post-fs-data && property:ro.debuggable=1
-    exec_background - root root -- clean_scratch_files
+    exec_background - root root -- /system/bin/clean_scratch_files