Revert "Bump datatables.net-buttons from 2.4.2 to 3.0.0 in /tcms"

This reverts commit 7927447.

Warning: Buttons requires DataTables 2 or newer

Fixes #3552

Author: atodorov

tcms/package-lock.json

@@ -2,7 +2,7 @@
   "dependencies": {
     "bootstrap-duration-picker": "2.1.3",
     "bootstrap-switch": "3.3.4",
-    "datatables.net-buttons": "3.0.0",
+    "datatables.net-buttons": "2.4.3",
     "html5sortable": "0.13.3",
     "jszip": "3.10.1",
     "patternfly": "3.59.5",