ci: adjust behavior of PUBLISH to be true for releases

Otherwise release builds never create the GitHub draft releases.
Not unless a user explicitly stats a build with `PUBLISH: true`.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

ci/Jenkinsfile.combined

@@ -26,7 +26,7 @@ pipeline {
     booleanParam(
       name: 'PUBLISH',
       description: 'Trigger publishing of build results for nightly or release.',
-      defaultValue: params.PUBLISH ?: false,
+      defaultValue: getPublishDefault(params.PUBLISH),
     )
   }
 
@@ -120,3 +120,13 @@ def List genChoices(String previousChoice, List defaultChoices) {
   choices.add(0, previousChoice)
   return choices
 }
+
+/* Helper that makes PUBLISH default to 'false' unless:
+ * - The build is for a release branch
+ * - A user explicitly specified a value
+ * Since release builds create and re-create GitHub drafts every time. */
+def Boolean getPublishDefault(Boolean previousValue) {
+  if (env.JOB_NAME.startsWith('status-react/release')) { return true }
+  if (previousValue != null) { return previousValue }
+  return false
+}