Merge changes from topic "RemoveReviewDbFromChangeNotes"

* changes:
  ChangeNotes: Remove ReviewDb-specific logic
  NotesMigration: Remove failChangeWrites() method
  NotesMigration: Remove disableChangeReviewDb() method


* submodules:
* Update plugins/reviewnotes from branch 'master'
  to b98d8920345aa6183fe98ea9bc15ae0fea5d9b58
  - Merge "Adapt to removal of ReviewDb-specific logic from ChangeNotes"
  - cmd-export: Remove reference to MySQL and PostgreSQL
    
    ReviewDb is gone, hence MySQL and PostgreSQL are no longer used.
    
    Change-Id: I2fa3ad412522c63ee71e2f8df073afc13fabe463
    Signed-off-by: Edwin Kempin <ekempin@google.com>
    
diff --git a/plugins/reviewnotes b/plugins/reviewnotes
index 25f0314..b98d892 160000
--- a/plugins/reviewnotes
+++ b/plugins/reviewnotes
@@ -1 +1 @@
-Subproject commit 25f0314fb6c8b3eb660b1b6221b6a4f2264bcfff
+Subproject commit b98d8920345aa6183fe98ea9bc15ae0fea5d9b58