* stable-2.16:
OutgoingEmail: Use UrlFormatter to get settings URL
CommentSender: Use UrlFormatter to get URLs for file and comments
Elasticsearch: Base the default number of shards on ES version
Disallow change index task duplication
AbstractPushForReview: Add tests for pushing with skip-validation option
Set version to 2.16.10-SNAPSHOT
Set version to 2.16.9
Documentation: Fix the Elasticsearch shards/replicas link
ProjectControl: Allow regexes ref strings for uploads
ProjectControl: Allow regexes ref strings for tags
ProjectControl: Reuse constants for ref strings
Add extension point to gr-user-header
Change-Id: I6a38b9bfdc2bcbb8c457ce24883767f4579ca656
3804d3ca51