Revert "Add modify_horizon_config script"

This change is not needed in the master branch.
Bug only affects updates from 5.0 to 5.0.2.
Later packages will be fixed.

This reverts commit 08d965e3aa3d0660dbbb5c1bb3bee04500e41542.

Change-Id: I13213b67e0c94c1bcae78fe197a4f233f7392208
Closes-Bug: 1356921