refat: removed unused devcontainer configuration

Author: mschead

.devcontainer/Dockerfile

@@ -2,7 +2,8 @@
 repo1-host=${BACKUP_HOST_IP}
 repo1-host-user=ubuntu
 repo1-path=/var/lib/pgbackrest
-repo1-retention-full=2
+repo1-retention-full=1
+repo1-retention-diff=7
 start-fast=y
 log-level-console=info
 log-level-file=info