OnlineNoteDbMigrationIT: Use local disk

Even though the migration is online so we only need to start a server
once, part of the migration process includes side effects of writing new
migration state to config files on disk.

Somewhat confusingly, the online migrator was actually writing contents
to a gerrit.config file on disk, even though that file was not where the
config used by the in-memory server was stored.

Change-Id: I0ba86907e01cd63eb006f876911e1d7d9a6eccef

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/notedb/OnlineNoteDbMigrationIT.java

diff --git a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/notedb/OnlineNoteDbMigrationIT.java b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/notedb/OnlineNoteDbMigrationIT.java
index f08a16e..0292aca 100644
--- a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/notedb/OnlineNoteDbMigrationIT.java
+++ b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/notedb/OnlineNoteDbMigrationIT.java
@@ -32,6 +32,7 @@
 import com.google.gerrit.acceptance.NoHttpd;
 import com.google.gerrit.acceptance.PushOneCommit;
 import com.google.gerrit.acceptance.Sandboxed;
+import com.google.gerrit.acceptance.UseLocalDisk;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;
@@ -65,6 +66,7 @@
 import org.junit.Test;
 
 @Sandboxed
+@UseLocalDisk
 @NoHttpd
 public class OnlineNoteDbMigrationIT extends AbstractDaemonTest {
   private static final String INVALID_STATE = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";