Buildbot: Attempt to resolve wrong path to the buildbot_upload.zip

It is expected to be in the build folder for the cmake.

Ideally it should be build/<builder> or install/<builder> but that's a bit more
involved change. Will look into it later.

build_files/buildbot/slave_pack.py

@@ -159,7 +159,7 @@ else:
         os.rename(result_file, "{}.zip".format(builderified_name))
         # create zip file
         try:
-            upload_zip = "buildbot_upload.zip"
+            upload_zip = "../buildbot_upload.zip"
             if os.path.exists(upload_zip):
                 os.remove(upload_zip)
             z = zipfile.ZipFile(upload_zip, "w", compression=zipfile.ZIP_STORED)