Build with API version 2.9.4
Build with API version 2.9.4

The latest Gerrit version on the 2.9 series is 2.9.4.

Also update the plugin version to be the same as the API version.

Change-Id: Ied2737da474b2b538c2b7efcc7a7abef2bd8f5aa

GerritCodeReview/plugins_branch-network,GerritCodeReview/plugins_branch-network