Enable improved user separation by default.

This is already on for all Pixel devices with no problems observed.

If this causes issues with a specific device (e.g. vendor apps being
unable to access their data) it can be temporarily disabled by adding

PRODUCT_PROPERTY_OVERRIDES += ro.vold.level_from_user=0

to the device.mk file. Please file a bug if that happens.

Bug: 141677108
Test: presubmits
Change-Id: Ic9da534f1a5f4c9e3bd62ea5c09a3b11ebcb33e7
Merged-In: Ic9da534f1a5f4c9e3bd62ea5c09a3b11ebcb33e7
(cherry picked from commit 763393644a0a6e361f26dfe26f6dc0021579f011)
diff --git a/FsCrypt.cpp b/FsCrypt.cpp
index ff8c1f4..8f6ba9c 100644
--- a/FsCrypt.cpp
+++ b/FsCrypt.cpp
@@ -795,7 +795,7 @@
 static bool prepare_subdirs(const std::string& action, const std::string& volume_uuid,
                             userid_t user_id, int flags) {
     // TODO(b/141677108): Remove this & make it the default behavior
-    if (android::base::GetProperty("ro.vold.level_from_user", "0") == "1") {
+    if (android::base::GetProperty("ro.vold.level_from_user", "1") == "1") {
         flags |= android::os::IVold::STORAGE_FLAG_LEVEL_FROM_USER;
     }