Revert "Disable javadoc publisher"

This reverts commit cbbd8b7.

Author: gilles-duboscq

Diff for: ci_includes/publish-javadoc.jsonnet

@@ -51,7 +51,7 @@
   },
 
   local all_builds = [
-    common.on_demand + linux_amd64 + common.labsjdk17 + javadoc_publisher,
+    common.post_merge + linux_amd64 + common.labsjdk17 + javadoc_publisher,
   ],
   // adds a "defined_in" field to all builds mentioning the location of this current file
   builds:: [{ defined_in: std.thisFile } + b for b in all_builds]