Use BRANCH jenkins variable in release script

scripts/release.js

 // Workaround JS
 const isRelease = process.env.RELEASE_BUILD === 'true';
 
-const BRANCH = process.env.GIT_BRANCH;
+const BRANCH = process.env.BRANCH;
 const VERSION_TAG = isRelease ? 'latest' : 'snapshot';
 const VERSION_INC = 'patch';