fs_mgr: Remove `include_dirs` declaration

We aren't using anything through the removed path.
We also shouldn't use `include_dirs` to begin with, as it bypasses any
build system checks.

Bug: 293695109
Test: build
Change-Id: I06f7450c3ce545aa2583f8c3f8db18c45073f69e
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index 0a836e4..7721ebf 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -60,7 +60,6 @@
     defaults: ["fs_mgr_defaults"],
     export_include_dirs: ["include"],
     local_include_dirs: ["include/"],
-    include_dirs: ["system/vold"],
     cflags: [
         "-D_FILE_OFFSET_BITS=64",
     ],