[DO-1037] add backup scripts (!6)

Reviewed-on: https://git.avroid.tech/DevOps/avroid_scripts/pulls/6

backup_scripts/postgres/post_backup.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+DIRBACKUP="/data/backups"
+
+if [ -d "${DIRBACKUP}" ]; then
+    rm -rf "${DIRBACKUP:?}/"*
+fi