Keystore 2.0: Move per-boot database out of SQLite

Being in SQLite incurs a variety of overheads. Originally, the per-boot
database was in SQLite with the intention of living in a temporary file
to allow keystore2 to restart without losing auth token state. Since
keystore2 is not allowed to crash, it was moved to an in-memory SQLite
database. Since it is no longer vfs backed, we do not need to pay the
memory, speed, and complexity costs of SQLite for it any longer.

Bug: 186436093
Test: atest keystore2_test
Test: atest CtsKeystoreTestCases
Change-Id: I5c219d294af1876a18a7fdef40307f3b92ae4b8b
diff --git a/keystore2/src/maintenance.rs b/keystore2/src/maintenance.rs
index a099d18..0633bc1 100644
--- a/keystore2/src/maintenance.rs
+++ b/keystore2/src/maintenance.rs
@@ -179,8 +179,8 @@
         check_keystore_permission(KeystorePerm::report_off_body())
             .context("In on_device_off_body.")?;
 
-        DB.with(|db| db.borrow_mut().update_last_off_body(MonotonicRawTime::now()))
-            .context("In on_device_off_body: Trying to update last off body time.")
+        DB.with(|db| db.borrow_mut().update_last_off_body(MonotonicRawTime::now()));
+        Ok(())
     }
 
     fn migrate_key_namespace(source: &KeyDescriptor, destination: &KeyDescriptor) -> Result<()> {